fix docs build

Author: snbianco

CHANGES.rst

@@ -17,8 +17,8 @@ Service fixes and enhancements
 mast
 ^^^^
 
-- Filtering by file extension or by a string column is now case-insensitive in `MastMissions.filter_products`
-  and `Observations.filter_products`. [#3427]
+- Filtering by file extension or by a string column is now case-insensitive in ``MastMissions.filter_products``
+  and ``Observations.filter_products``. [#3427]
 
 
 Infrastructure, Utility and Other Changes and Additions