DOCSP-33881 mongdump $regex example (#114)

* DOCSP-33881 mongdump  example

* JM feedback

* FH feedback

Author: ajhuh-mdb

source/mongodump.txt

@@ -706,6 +706,12 @@ Options
 
       mongodump -d=test -c=records -q='{ "a": { "$gte": 3 }, "date": { "$lt": { "$date": "2016-01-01T00:00:00.000Z" } } }'
 
+   To use :query:`$regex` with ``mongodump``, use the following syntax: 
+
+   .. code-block:: sh 
+
+      mongodump -d=sample_mflix -c=movies -q='{ "year": { "$regex": "20" } }'
+
    .. note::
 
       When you use the ``--query`` option on a :ref:`time series