DOCSP-32833 address feedback on Query Your Data (#593)

Author: kanchana-mongodb

source/query/filter.txt

@@ -342,6 +342,36 @@ For more query examples, see
 :manual:`Query Documents </tutorial/query-documents/>` 
 in the MongoDB manual.
 
+Match by Substring 
+~~~~~~~~~~~~~~~~~~
+
+The following query filter uses the :query:`$regex` operator
+to find all documents where the value of ``email`` includes the term
+"andrea_le":
+
+.. code-block:: shell
+
+   { email: { $regex: "andrea_le" } }
+
+The query returns the following document:
+
+.. code-block:: JSON
+   :copyable: false
+   :emphasize-lines: 4
+
+   {
+      "_id": { "$oid": "5e349915cebae490877d561d" },
+      "name": "Andrea Le",
+      "email": "[email protected]",
+      "version": 5,
+      "scores": [ 85, 95, 75 ],
+      "dateCreated": { "$date": "2003-03-26" }
+   }
+
+For more query examples, see 
+:manual:`Query Documents </tutorial/query-documents/>` 
+in the MongoDB manual.
+
 Supported Data Types in the Query Bar
 -------------------------------------