DOCS-11983 add blurb to release notes

Author: Isabella Siu

source/release-notes/4.2.txt

@@ -84,6 +84,15 @@ MongoDB removes the deprecated option ``maxScan`` for the
 ``cursor.maxScan()``. Use either the ``maxTimeMS`` option for the
 :dbcommand:`find` command or the helper :method:`cursor.maxTimeMS()` instead.
 
+General Improvements
+--------------------
+
+``outputConfig`` Option
+~~~~~~~~~~~~~~~~~~~~~~~
+
+MongoDB 4.2 adds the :option:`--outputConfig <mongod --outputConfig>` option for 
+:binary:`~bin.mongod` and :binary:`~bin.mongos`, which outputs the resolved 
+YAML configuration document to ``stdout`` and halts the server instance.
 
 Changes Affecting Compatibility
 -------------------------------