DOCSP-16529 Clarifies source/destination clusters on Quickstart (#235)

* DOCSP-16529 Clarifies source/destination clusters on Quickstart

* Fixes per Ashley

* Fixes per Ashley

* Fixes per Ajay

Author: kennethdyer

source/quickstart.txt

@@ -4,7 +4,6 @@
 Quickstart
 ==========
 
-
 .. default-domain:: mongodb
 
 .. contents:: On this page
@@ -25,15 +24,27 @@ the rest of the {+c2c-product-name+} documentation.
 Setup
 -----
 
-{+c2c-product-name+} syncs data between two clusters. To run
-``mongosync``, you will need to: 
+``mongosync`` syncs data between two clusters. 
+
+- Each cluster can be a replica set or a sharded cluster.  If either
+  is a sharded cluster, consult the :ref:`sharded cluster limitations
+  <c2c-sharded-limitations>` for ``mongosync``.
+
+- Sharded clusters are not required to have the same number of shards.
+
+- The destination cluster must be the same version or up to two versions ahead
+  of the source cluster. The patch version is not important, so long as they 
+  meets the minimum patch :ref:`version requirements
+  <c2c-server-version-compatibility>`.
+
+To run ``mongosync``, you need to: 
 
 #. Define a source and a destination cluster.
 #. Define administrative users.
 #. Download and install ``mongosync``.
 #. Connect the clusters.
 
-Follow the instructions below to setup {+c2c-product-name+}.
+Follow the instructions below to set up {+c2c-product-name+}.
 
 .. procedure::
    :style: normal

source/reference/limitations.txt

@@ -70,6 +70,8 @@ Unsupported Collection Types
 - Clustered collections with :ref:`expireAfterSeconds
   <db.createCollection.expireAfterSeconds>` set aren't supported.
 
+.. _c2c-sharded-limitations:
+
 Sharded Clusters
 ----------------