DOCSP-10640: [Kafka] Users can implement their own WriteModelStrategy

Author: steveren

source/kafka-sink-postprocessors.txt

@@ -691,10 +691,14 @@ strategies are provided with the connector:
      - | Add ``_insertedTS`` (inserted timestamp) and ``_modifiedTS`` (modified timestamp) fields into documents that match the filters provided by the ``document.id.strategy`` setting.
        | Set the following configuration: ``writemodel.strategy=com.mongodb.kafka.connect.sink.writemodel.strategy.UpdateOneBusinessKeyTimestampStrategy``
 
-.. note::
-
-   Future versions of the MongoDB Kafka Connector will allow developers to
-   specify a user-created, custom strategy in the configuration settings.
+Create Your Own Custom Write Strategy
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+If none of the pre-built write strategy models suits your needs, you can
+create your own. A custom write strategy model is a Java class that implements
+``WriteModelStrategy``. Specify your Java class in the 
+``mongodb.writemodel.strategy`` :ref:`configuration setting
+<kafka-sink-properties>`.
 
 .. _writemodel-strategy-business-key:
 

source/kafka-sink-properties.txt

@@ -219,7 +219,9 @@ data to sink to MongoDB. For an example configuration file, see
 
    * - writemodel.strategy
      - string
-     - | The class that specifies the ``WriteModel`` to use for :manual:`Bulk Writes </core/bulk-write-operations/index.html>`.
+     - | The class that specifies the ``WriteModel`` to use for :manual:`Bulk
+         Writes </core/bulk-write-operations/index.html>`. See :ref:`Custom
+         Write Models <custom-write-models>` for more information.
        |
        | **Default**: ``com.mongodb.kafka.connect.sink.writemodel.strategy.ReplaceOneDefaultStrategy``
        | **Accepted Values**: A fully qualified Java class name of a class that implements ``WriteModelStrategy``