DOCS-11896: 4.2 reindex restriction on mongos

Author: kay-kim

source/reference/command/reIndex.txt

@@ -23,7 +23,15 @@ reIndex
 
       - Avoid running :dbcommand:`reIndex` for a replica set.
 
-      - Do not run :dbcommand:`reIndex` for a sharded cluster.
+      - Do not run :dbcommand:`reIndex` against a collection in a
+        sharded cluster.
+
+        .. versionchanged:: 4.2
+
+           MongoDB disallows :dbcommand:`reIndex` to be run on a
+           :binary:`~bin.mongos`, implementing a stronger restriction
+           against running :dbcommand:`reIndex` for a collection in a
+           sharded cluster.
 
    Use the following syntax:
 

source/reference/method/db.collection.reIndex.txt

@@ -28,6 +28,13 @@ db.collection.reIndex()
       - Do not run :method:`db.collection.reIndex()` against a
         collection in a sharded cluster.
 
+        .. versionchanged:: 4.2
+
+           MongoDB disallows :method:`db.collection.reIndex()` to be
+           run on a :binary:`~bin.mongos`, implementing a stronger
+           restriction against running
+           :method:`db.collection.reIndex()` for a collection in a
+           sharded cluster.
 
 Behavior
 --------

source/release-notes/4.2-compatibility.txt

@@ -133,6 +133,15 @@ As alternatives:
   :doc:`/tutorial/recover-data-following-unexpected-shutdown` for
   details.
 
+General Changes
+---------------
+
+- MongoDB implements a stronger restriction on running
+  :dbcommand:`reIndex` command and :method:`db.collection.reIndex()`
+  shell helper against a collection in a sharded cluster by disallowing
+  :dbcommand:`reIndex` and :method:`db.collection.reIndex()` on a
+  :binary:`~bin.mongos`.
+           
 .. _4.2-compatibility-enabled:
 
 4.2 Feature Compatibilitity