DOCSP-16274: source connector regex example fix (#106)

Author: Chris Cho

source/kafka-source.txt

@@ -464,7 +464,7 @@ an example source connector configuration file, see
      - | Name of topic to use as the dead letter queue. If blank, the connector
          does not write invalid messages to the dead letter queue. If a value is
          provided, the connector writes invalid messages to the dead letter
-         queue as :manual:`extended JSON strings </reference/mongodb-extended-json/>`. 
+         queue as :manual:`extended JSON strings </reference/mongodb-extended-json/>`.
        |
        | **errors.tolerance** must be set to ``all`` to use this property.
        |
@@ -491,10 +491,10 @@ an example source connector configuration file, see
          change stream. The connector sends heartbeat messages when
          source records are not published in the specified interval.
          This improves the resumability of the connector for low volume
-         namespaces. See the 
+         namespaces. See the
          :ref:`Invalid Resume Token section <source-invalid-resume-token>`
          of this page for more information on the problem this feature can help
-         solve. Use ``0`` to disable. 
+         solve. Use ``0`` to disable.
        | **Default**: ``0``
        | **Accepted Values**: An integer
 
@@ -591,7 +591,7 @@ ones in the collection named "customers":
 
 .. code-block:: properties
 
-   "pipeline":[{"$match": {"ns.coll": {"$regex": "/^(?!customers\.).*/"}}}]
+   "pipeline":[{"$match": {"ns.coll": {"$regex": "/^(?!customers$).*/"}}}]
 
 For more information on how to build regular expressions, see the
 `Java SE documentation on Patterns <https://docs.oracle.com/javase/8/docs/api/java/util/regex/Pattern.html>`__.
@@ -744,6 +744,6 @@ workers and listen to the change stream.
    MongoDB namespace being infrequently updated, consider enabling the heartbeat
    feature. This feature periodically updates the Change stream resume token to the current entry in
    your MongoDB Oplog if no updates occurred in your source MongoDB namespace.
-   To learn how to enable heartbeats, see the 
+   To learn how to enable heartbeats, see the
    :ref:`Source Connector Configuration Properties section <source-connector-configuration-properties>`.
-   
+