Docsp 30395 adding index consistency limitations (#168)

* DOCSP-30395 Indicate that mongosync will only sync indexes with consistent specs on all shards

* DOCSP-30395 adding note

* DOCSP-30395 adding note

Author: ltran-mdb2

source/reference/limitations.txt

@@ -115,7 +115,15 @@ Sharded Clusters
 - There is no replication for zone configuration. ``mongosync``
   replicates data, it does not inherit zones.
 - Shards cannot be added or removed while syncing.
-- Only indexes which exist on all shards are synced.
+- ``mongosync`` only syncs indexes that exist on all shards. 
+- ``mongosync`` only syncs indexes that have consistent index
+  specifications on all shards. 
+
+.. note::
+
+  To check for index inconsistencies, see :ref:`Find Inconsistent
+  Indexes Across Shards <manage-indexes-find-inconsistent-indexes>`.
+
 - The shard key cannot be :ref:`refined <shard-key-refine>` while
   syncing.
 - The shard key cannot be modified using :dbcommand:`reshardCollection`