Fix JSX v4 spec about configuration (#719)

Author: mununki

cli/JSXV4.md

@@ -18,16 +18,26 @@ To build an entire project in V4 mode, including all its dependencies, use the n
 ### Dependency-level config
 
 Dependencies inherit the `jsx` configuration of the root project. So if the root project uses V4 then the dependencies are built using V4, and the same for V3.
-To build certain dependencies in V3 compatibility mode, whatever the version used in the root project, use `"v3-dependencies"` as in the example:
+To build certain dependencies in V3 compatibility mode, whatever the version used in the root project, use `"v3-dependencies"`: the listed dependencies will be built in V3 mode, and in addition `-open ReatcV3` is added to the compiler options.
+
+For example, suppose a V3 project uses rescript-react 0.11, which requires compatibility mode if compiled with V3, and that 2 dependencies `"rescript-react-native", "rescript-react-navigation"` only build with compatibility mode. Then the setting will be:
 
 ```json
 "jsx": {
- "version": 4,
- "v3-dependencies": ["rescript-react-native", "rescript-react-navigation"]
-}
+  "version": 3,
+  "v3-dependencies": ["rescript-react-native", "rescript-react-navigation"]
+},
+"bsc-flags": ["-open ReactV3"]
 ```
 
-In V3 compatibility mode, the listed dependencies are built in V3 mode, and in addition `-open ReatcV3` is added to the compiler options, so that the `ReactV3` compatibility module in rescript-react is used.
+Another example is a V4 project that also uses `"rescript-react-native", "rescript-react-navigation"`. Then the setting will be:
+
+```json
+"jsx": {
+  "version": 4,
+  "v3-dependencies": ["rescript-react-native", "rescript-react-navigation"]
+}
+```
 
 > Note: do not add @rescript/react to the v3-dependencies, or it will cause a cyclic dependencies error.
 
@@ -378,7 +388,6 @@ let p: A.props<_> = {x: "x", y: "y"}
 
 V4 introduces support to control the definition of the `props` type by passing as argument to `@react.component` the body of the type definition of `props`. The main application is sharing a single type definition across several components. Here are a few examples:
 
-
 ```rescript
 type sharedprops<'x, 'y> = {x: 'x, y: 'y, z:string}
 
@@ -400,6 +409,7 @@ module C3 = {
 ```
 
 The generated code (some details removed) looks like this:
+
 ```rescript
 @@jsxConfig({version: 4, mode: "classic"})