Docs 14117 json formatter edits (#80)

DOCS 14117 update default json formatter and link to formatter descriptions

Author: biniona-mongodb

source/kafka-source.txt

@@ -192,14 +192,20 @@ an example source connector configuration file, see
 
    * - output.json.formatter
      - string
-     - | Full class name of the JSON formatter.
+     - | Full class name of the JSON formatter. You can also provide your own custom JSON formatter. 
        |
-       | **Default**: ``com.mongodb.kafka.connect.source.json.formatter.ExtendedJson``
+       | **Default**: ``com.mongodb.kafka.connect.source.json.formatter.DefaultJson``
        | **Accepted Values**:
        | - ``com.mongodb.kafka.connect.source.json.formatter.DefaultJson``
        | - ``com.mongodb.kafka.connect.source.json.formatter.ExtendedJson``
        | - ``com.mongodb.kafka.connect.source.json.formatter.SimplifiedJson``
-       | - Or other user-provided class name
+       | - Or your custom JSON formatter class name
+
+       .. seealso::
+
+          - `Extended JSON \(MongoDB Extended JSON\) <https://github.com/mongodb/specifications/blob/master/source/extended-json.rst#abstract>`__
+          - `Default JSON \(IETF JSON\) <https://tools.ietf.org/html/rfc7159>`__
+          - `Simplified JSON \(MongoDB Relaxed Extended JSON\) <https://github.com/mongodb/specifications/blob/master/source/extended-json.rst#relaxed-extended-json-example>`__
 
    * - output.schema.key
      - string