DOCSP-13806: add note about $uuid parsing in extended json (#62)

DOCSP-13806: add note about $uuid parsing in extended json 
Co-authored-by: Nathan <[email protected]>

Author: biniona-mongodb

source/fundamentals/data-formats/document-data-format-extended-json.txt

@@ -70,6 +70,16 @@ See the table below to see a description of each format:
 
 .. _extended_json_example_section:
 
+.. note::
+
+   The ``$uuid`` Extended JSON type is parsed from a String to a
+   :java-docs:`BsonBinary </apidocs/bson/org/bson/BsonBinary.html#<init>(java.util.UUID)>`
+   object of binary subtype 4. For more information about ``$uuid`` field
+   parsing, see the
+   :spec:`special rules for parsing $uuid fields </extended-json.rst#special-rules-for-parsing-uuid-fields>`
+   section in the extended JSON specification.
+   
+
 For more detailed information on these formats, see the
 `Extended JSON specification <https://github.com/mongodb/specifications/blob/master/source/extended-json.rst>`__.