DOCSP-23884 clarify shard docs (#77)

* DOCSP--23884 Refactor of Connect step

* DOCSP-23884 Refactor of Connect step

* DOCSP-23884 Refactor of Connect step

* DOCSP-23884 Fixes per Joe

* DOCSP-23884 Fixes per Lingzhi Deng

Author: kennethdyer

source/multiple-mongosyncs.txt

@@ -102,17 +102,7 @@ To configure multiple ``mongosync`` instances:
          A single host server can run multiple ``mongosync`` instances. To
          improve performance, run ``mongosync`` on multiple host servers.
 
-      Each ``mongosync`` instance:
-
-      - Connects to the same ``mongos`` instance in the source cluster.
-      - Connects to the same ``mongos`` instance in the destination
-        cluster.
-      - Connects to a single shard in the source cluster.
-      - Specifies a unique port to use for during synchronization.
-        Consider designating a range of ports to simplify scripting
-        {+c2c-product-name+} operations.
-
-      Run the first ``mongosync`` instance:
+      Run the first ``mongosync`` instance, connecting to ``mongos``.  
 
       .. code-block:: javascript
 
@@ -121,8 +111,13 @@ To configure multiple ``mongosync`` instances:
            --cluster1 "mongodb://user:password@cluster1host:27500" \
            --id shard01 --port 27601
 
+      When running multiple ``mongosync`` instances, the number of instances
+      must equal the number of shards.  Each ``mongosync`` instance must be
+      started with the :option:`--id` option or :setting:`id` setting to
+      specify the shard it replicates.
+
       Run a new ``mongosync`` instance for each shard in the source cluster.
-      Edit the ``--id`` and ``--port`` fields for each additional
+      Edit the :option:`--id` and :option:`--port` options for each additional
       ``mongosync`` instance.
 
       .. code-block:: javascript
@@ -133,6 +128,20 @@ To configure multiple ``mongosync`` instances:
            --cluster1 "mongodb://user:password@cluster1host:27500" \
            --id shard02 --port 27602
 
+      The connection strings for the :option:`--cluster0` and 
+      :option:`--cluster1` options should point to ``mongos`` instances.
+      In the example, they use the same ``mongos`` instance.
+
+      Each ``mongosync`` instance:
+
+      - Connects to ``mongos`` instances in the source cluster.
+      - Connects to ``mongos`` instances in the destination cluster.
+      - Replicates a single shard from the source cluster, 
+        identified by the :option:`--id` option.
+      - Specifies a unique port to use during synchronization.
+        Consider designating a range of ports to simplify scripting
+        {+c2c-product-name+} operations.
+
 .. _c2c-sharded-start:
 
 Start Multiple ``mongosync`` Instances