Removed references to empty strings as null values

Author: clintongormley

052_Mapping_Analysis/50_Complex_datatypes.asciidoc

@@ -50,7 +50,6 @@ indexed:
 
 [source,js]
 --------------------------------------------------
-"empty_string":             "",
 "null_value":               null,
 "empty_array":              [],
 "array_with_null_value":    [ null ]

080_Structured_Search/30_existsmissing.asciidoc

@@ -20,7 +20,7 @@ can't!  An inverted index is simply a list of tokens and the documents that
 contain them.  If a field doesn't exist, it doesn't hold any tokens, which
 means it won't be represented in an inverted index data structure.
 
-Ultimately, this((("strings", "empty")))((("arrays", "empty"))) means that a `null`, `""` (an empty string), `[]` (an empty
+Ultimately, this((("strings", "empty")))((("arrays", "empty"))) means that a `null`, `[]` (an empty
 array), and `[null]` are all equivalent. They simply don't exist in the
 inverted index!