Update note (#134)

Author: davidhou17

source/atlasdeployment-custom-resource.txt

@@ -743,13 +743,18 @@ examples, and the |api| documentation.
         - :manual:`Sharding </sharding>`
         - :ref:`server-number-costs`
 
-   .. note:: 
-
-      To ensure consistent data distribution, you can't increase the number 
-      of shards in the same update request when upgrading your {+cluster+} 
-      from a replica set to a sharded {+cluster+}. You can add additional shards 
-      when your {+cluster+} has upgraded and you've ensured all clients have 
-      reconnected to the MongoDB router.
+   .. warning:: 
+
+      When you use a sharded cluster, MongoDB requires that your applications connect 
+      to a |mongos| instance to ensure that your applications interact with the shards 
+      and other components of the sharded cluster properly. 
+      If you migrate from a replica set to a sharded cluster, your
+      applications must restart to enable the connection 
+      to the cluster's |mongos|. As a result, the Atlas Admin API 
+      prevents you from migrating a replica set directly to a sharded cluster 
+      with more than one shard. After you successfully migrate your replica set 
+      to a single shard cluster and reset your application connections,
+      you can add additional shards to the cluster.
 
 .. setting:: spec.deploymentSpec.replicationSpecs.regionConfigs