doc: stripped line trailing whitespaces.

Signed-off-by: Yichun Zhang (agentzh) <agentzh@gmail.com>

Author: alubbe

README.markdown

@@ -623,9 +623,9 @@ Known Issues
 
 TCP socket connect operation issues
 -----------------------------------
-The [tcpsock:connect](#tcpsockconnect) method may indicate `success` despite connection failures such as with `Connection Refused` errors. 
+The [tcpsock:connect](#tcpsockconnect) method may indicate `success` despite connection failures such as with `Connection Refused` errors.
 
-However, later attempts to manipulate the cosocket object will fail and return the actual error status message generated by the failed connect operation. 
+However, later attempts to manipulate the cosocket object will fail and return the actual error status message generated by the failed connect operation.
 
 This issue is due to limitations in the Nginx event model and only appears to affect Mac OS X.
 
@@ -755,7 +755,7 @@ To avoid this, *double* escape the backslash:
 
 Here, `\\\\d+` is stripped down to `\\d+` by the Nginx config file parser and this is further stripped down to `\d+` by the Lua language parser before running.
 
-Alternatively, the regex pattern can be presented as a long-bracketed Lua string literal by encasing it in "long brackets", `[[...]]`, in which case backslashes have to only be escaped once for the Nginx config file parser. 
+Alternatively, the regex pattern can be presented as a long-bracketed Lua string literal by encasing it in "long brackets", `[[...]]`, in which case backslashes have to only be escaped once for the Nginx config file parser.
 
 ```nginx
 
@@ -772,7 +772,7 @@ Alternatively, the regex pattern can be presented as a long-bracketed Lua string
 
 Here, `[[\\d+]]` is stripped down to `[[\d+]]` by the Nginx config file parser and this is processed correctly.
 
-Note that a longer from of the long bracket, `[=[...]=]`, may be required if the regex pattern contains `[...]` sequences. 
+Note that a longer from of the long bracket, `[=[...]=]`, may be required if the regex pattern contains `[...]` sequences.
 The `[=[...]=]` form may be used as the default form if desired.
 
 ```nginx
@@ -788,7 +788,7 @@ The `[=[...]=]` form may be used as the default form if desired.
  # evaluates to "1234"
 ```
 
-An alternative approach to escaping PCRE sequences is to ensure that Lua code is placed in external script files and executed using the various `*_by_lua_file` directives. 
+An alternative approach to escaping PCRE sequences is to ensure that Lua code is placed in external script files and executed using the various `*_by_lua_file` directives.
 With this approach, the backslashes are only stripped by the Lua language parser and therefore only need to be escaped once each.
 
 ```lua
@@ -800,8 +800,8 @@ With this approach, the backslashes are only stripped by the Lua language parser
  -- evaluates to "1234"
 ```
 
-Within external script files, PCRE sequences presented as long-bracketed Lua string literals do not require modification. 
- 
+Within external script files, PCRE sequences presented as long-bracketed Lua string literals do not require modification.
+
 ```lua
 
  -- test.lua
@@ -1152,7 +1152,7 @@ The ngx_lua module does not support the `stat` mode available with the
 Apache `mod_lua` module (yet).
 
 Disabling the Lua code cache is strongly
-discouraged for production use and should only be used during 
+discouraged for production use and should only be used during
 development as it has a significant negative impact on overall performance. For example, the performance a "hello world" Lua example can drop by an order of magnitude after disabling the Lua code cache.
 
 [Back to TOC](#directives)
@@ -1538,15 +1538,15 @@ set_by_lua_file
 
 **phase:** *rewrite*
 
-Equivalent to [set_by_lua](#set_by_lua), except that the file specified by `<path-to-lua-script-file>` contains the Lua code, or, as from the `v0.5.0rc32` release, the [Lua/LuaJIT bytecode](#lualuajit-bytecode-support) to be executed. 
+Equivalent to [set_by_lua](#set_by_lua), except that the file specified by `<path-to-lua-script-file>` contains the Lua code, or, as from the `v0.5.0rc32` release, the [Lua/LuaJIT bytecode](#lualuajit-bytecode-support) to be executed.
 
 Nginx variable interpolation is supported in the `<path-to-lua-script-file>` argument string of this directive. But special care must be taken for injection attacks.
 
 When a relative path like `foo/bar.lua` is given, they will be turned into the absolute path relative to the `server prefix` path determined by the `-p PATH` command-line option while starting the Nginx server.
 
-When the Lua code cache is turned on (by default), the user code is loaded once at the first request and cached 
+When the Lua code cache is turned on (by default), the user code is loaded once at the first request and cached
 and the Nginx config must be reloaded each time the Lua source file is modified.
-The Lua code cache can be temporarily disabled during development by 
+The Lua code cache can be temporarily disabled during development by
 switching [lua_code_cache](#lua_code_cache) `off` in `nginx.conf` to avoid reloading Nginx.
 
 This directive requires the [ngx_devel_kit](https://github.com/simpl/ngx_devel_kit) module.
@@ -1565,7 +1565,7 @@ content_by_lua
 **WARNING** Since the `v0.9.17` release, use of this directive is *discouraged*;
 use the new [content_by_lua_block](#content_by_lua_block) directive instead.
 
-Acts as a "content handler" and executes Lua code string specified in `<lua-script-str>` for every request. 
+Acts as a "content handler" and executes Lua code string specified in `<lua-script-str>` for every request.
 The Lua code may make [API calls](#nginx-api-for-lua) and is executed as a new spawned coroutine in an independent global environment (i.e. a sandbox).
 
 Do not use this directive and other content handler directives in the same location. For example, this directive and the [proxy_pass](http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_pass) directive should not be used in the same location.
@@ -1614,9 +1614,9 @@ Nginx variables can be used in the `<path-to-lua-script-file>` string to provide
 
 When a relative path like `foo/bar.lua` is given, they will be turned into the absolute path relative to the `server prefix` path determined by the `-p PATH` command-line option while starting the Nginx server.
 
-When the Lua code cache is turned on (by default), the user code is loaded once at the first request and cached 
+When the Lua code cache is turned on (by default), the user code is loaded once at the first request and cached
 and the Nginx config must be reloaded each time the Lua source file is modified.
-The Lua code cache can be temporarily disabled during development by 
+The Lua code cache can be temporarily disabled during development by
 switching [lua_code_cache](#lua_code_cache) `off` in `nginx.conf` to avoid reloading Nginx.
 
 Nginx variables are supported in the file path for dynamic dispatch, for example:
@@ -1934,7 +1934,7 @@ Nginx variables can be used in the `<path-to-lua-script-file>` string to provide
 
 When a relative path like `foo/bar.lua` is given, they will be turned into the absolute path relative to the `server prefix` path determined by the `-p PATH` command-line option while starting the Nginx server.
 
-When the Lua code cache is turned on (by default), the user code is loaded once at the first request and cached 
+When the Lua code cache is turned on (by default), the user code is loaded once at the first request and cached
 and the Nginx config must be reloaded each time the Lua source file is modified.
 The Lua code cache can be temporarily disabled during development by switching [lua_code_cache](#lua_code_cache) `off` in `nginx.conf` to avoid repeatedly reloading Nginx.
 
@@ -2175,7 +2175,7 @@ Runs the Lua source code inlined as the `<lua-script-str>` at the `log` request
 Note that the following API functions are currently disabled within this context:
 
 * Output API functions (e.g., [ngx.say](#ngxsay) and [ngx.send_headers](#ngxsend_headers))
-* Control API functions (e.g., [ngx.exit](#ngxexit)) 
+* Control API functions (e.g., [ngx.exit](#ngxexit))
 * Subrequest API functions (e.g., [ngx.location.capture](#ngxlocationcapture) and [ngx.location.capture_multi](#ngxlocationcapture_multi))
 * Cosocket API functions (e.g., [ngx.socket.tcp](#ngxsockettcp) and [ngx.req.socket](#ngxreqsocket)).
 
@@ -3439,7 +3439,7 @@ ngx.ctx
 -------
 **context:** *init_worker_by_lua&#42;, set_by_lua&#42;, rewrite_by_lua&#42;, access_by_lua&#42;, content_by_lua&#42;, header_filter_by_lua&#42;, body_filter_by_lua&#42;, log_by_lua&#42;, ngx.timer.&#42;, balancer_by_lua&#42;*
 
-This table can be used to store per-request Lua context data and has a life time identical to the current request (as with the Nginx variables). 
+This table can be used to store per-request Lua context data and has a life time identical to the current request (as with the Nginx variables).
 
 Consider the following example,
 
@@ -3702,7 +3702,7 @@ The `args` option can also take plain query strings:
 
 This is functionally identical to the previous examples.
 
-The `share_all_vars` option controls whether to share nginx variables among the current request and its subrequests. 
+The `share_all_vars` option controls whether to share nginx variables among the current request and its subrequests.
 If this option is set to `true`, then the current request and associated subrequests will share the same Nginx variable scope. Hence, changes to Nginx variables made by a subrequest will affect the current request.
 
 Care should be taken in using this option as variable scope sharing can have unexpected side effects. The `args`, `vars`, or `copy_all_vars` options are generally preferable instead.
@@ -3769,7 +3769,7 @@ In addition to the two settings above, it is possible to specify
 values for variables in the subrequest using the `vars` option. These
 variables are set after the sharing or copying of variables has been
 evaluated, and provides a more efficient method of passing specific
-values to a subrequest over encoding them as URL arguments and 
+values to a subrequest over encoding them as URL arguments and
 unescaping them in the Nginx config file.
 
 ```nginx
@@ -3854,7 +3854,7 @@ Note that subrequests issued by [ngx.location.capture](#ngxlocationcapture) inhe
 request headers of the current request by default and that this may have unexpected side effects on the
 subrequest responses. For example, when using the standard `ngx_proxy` module to serve
 subrequests, an "Accept-Encoding: gzip" header in the main request may result
-in gzipped responses that cannot be handled properly in Lua code. Original request headers should be ignored by setting 
+in gzipped responses that cannot be handled properly in Lua code. Original request headers should be ignored by setting
 [proxy_pass_request_headers](http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_pass_request_headers) to `off` in subrequest locations.
 
 When the `body` option is not specified and the `always_forward_body` option is false (the default value), the `POST` and `PUT` subrequests will inherit the request bodies of the parent request (if any).
@@ -3994,7 +3994,7 @@ will yield
  Set-Cookie: b=4; path=/
 ```
 
-in the response headers. 
+in the response headers.
 
 Only Lua tables are accepted (Only the last element in the table will take effect for standard headers such as `Content-Type` that only accept a single value).
 
@@ -4026,7 +4026,7 @@ The same applies to assigning an empty table:
 
 Setting `ngx.header.HEADER` after sending out response headers (either explicitly with [ngx.send_headers](#ngxsend_headers) or implicitly with [ngx.print](#ngxprint) and similar) will throw out a Lua exception.
 
-Reading `ngx.header.HEADER` will return the value of the response header named `HEADER`. 
+Reading `ngx.header.HEADER` will return the value of the response header named `HEADER`.
 
 Underscores (`_`) in the header names will also be replaced by dashes (`-`) and the header names will be matched case-insensitively. If the response header is not present at all, `nil` will be returned.
 
@@ -4537,7 +4537,7 @@ That is, they will take Lua boolean values `true`. However, they are different f
 
 Empty key arguments are discarded. `POST /test` with body `=hello&=world` will yield empty outputs for instance.
 
-Note that a maximum of 100 request arguments are parsed by default (including those with the same name) and that additional request arguments are silently discarded to guard against potential denial of service attacks.  
+Note that a maximum of 100 request arguments are parsed by default (including those with the same name) and that additional request arguments are silently discarded to guard against potential denial of service attacks.
 
 However, the optional `max_args` function argument can be used to override this limit:
 
@@ -4598,7 +4598,7 @@ the value of `ngx.req.get_headers()["Foo"]` will be a Lua (array) table such as:
  {"foo", "bar", "baz"}
 ```
 
-Note that a maximum of 100 request headers are parsed by default (including those with the same name) and that additional request headers are silently discarded to guard against potential denial of service attacks.  
+Note that a maximum of 100 request headers are parsed by default (including those with the same name) and that additional request headers are silently discarded to guard against potential denial of service attacks.
 
 However, the optional `max_headers` function argument can be used to override this limit:
 
@@ -6007,7 +6007,7 @@ When the `replace` is a string, then it is treated as a special template for str
 
 where `$0` referring to the whole substring matched by the pattern and `$1` referring to the first parenthesized capturing substring.
 
-Curly braces can also be used to disambiguate variable names from the background string literals: 
+Curly braces can also be used to disambiguate variable names from the background string literals:
 
 ```lua