DOCSP-38018 Add Note Mongosync Cannot Mid Upgrade (#307)

* DOCSP-38018 Add Note Mongosync Cannot Mid Upgrade

* DOCSP-38018 Add Upgrade Consideraton

* XR

Author: ianf-mongodb

source/reference/limitations.txt

@@ -54,10 +54,11 @@ General Limitations
 - .. include:: /includes/fact-applyOps.rst
 - ``mongosync`` must read from the source cluster using the 
   :readmode:`primary` read preference.
+- ``mongosync`` does not support source or destination clusters that 
+  are currently upgrading MongoDB versions.
 - ``mongosync`` does not support syncing 
   `Atlas Search Indexes <https://www.mongodb.com/docs/atlas/atlas-search/create-index/>`__.
 
-
 MongoDB Community Edition
 -------------------------
 

source/reference/versioning.txt

@@ -219,4 +219,3 @@ Patch Releases
 - Changes to informational text in API responses, but not changes to
   enum-style string fields like "state".
 - Typo fixes.
-