DOCSP-12730: add exclusion example (#63)

* DOCSP-12730: add exclusion example

Author: Chris Cho

source/kafka-source.txt

@@ -492,6 +492,18 @@ collections by matching with a regular expression on the collection names:
 
    pipeline=[{"$match": {"ns.coll": {"$regex": /^(collection1|collection2)$/}}}]
 
+You can also set a regular expression to match all collections except for
+ones that match specific names. The following sample configuration shows
+how you can set your source connector to listen to all collections except
+ones in the collection named "customers":
+
+.. code-block:: properties
+
+   "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>`__.
+
 .. _topic-naming-example:
 
 Topic Naming Example