Update kinesis.md to add documentation for new configuration (#9585)

* Update kinesis.md to add documentation for new configuration

Signed-off-by: Saketh, Pallempati <Pallempati.Saketh@fmr.com>

* Update _data-prepper/pipelines/configuration/sources/kinesis.md

Co-authored-by: Naarcha-AWS <97990722+Naarcha-AWS@users.noreply.github.com>
Signed-off-by: Saketh Pallempati <saketh.pallempati@gmail.com>

---------

Signed-off-by: Saketh, Pallempati <Pallempati.Saketh@fmr.com>
Signed-off-by: Saketh Pallempati <saketh.pallempati@gmail.com>
Co-authored-by: Naarcha-AWS <97990722+Naarcha-AWS@users.noreply.github.com>

Author: saketh-pallempati

_data-prepper/pipelines/configuration/sources/kinesis.md

@@ -69,6 +69,8 @@ Option | Required | Type    | Description
 `key_name` | No | String | The name of the input field from which to extract the JSON array and create Data Prepper events.
 `include_keys` | No | List | The list of input fields to be extracted and added as additional fields in the Data Prepper event.
 `include_keys_metadata` | No | List | The list of input fields to be extracted and added to the Data Prepper event metadata object.
+`max_event_length` | No | Integer | The maximum size of any single event being read by the JSON codec. Default is 20,000,000 characters.
+
 
 ### `newline` codec