DOCSP-30831 mongosync Commit Behavior Clarification (#188)

* DOCSP-30831 mongosync Commit Behavior Clarification

* more explicit default behavior spec

* copy

* rebase

Author: ajhuh-mdb

source/reference/mongosync.txt

@@ -217,17 +217,16 @@ Commit
 ~~~~~~
 
 To stop syncing, use the :ref:`commit <c2c-api-commit>` command on the
-destination cluster to convert indexes and finalize the changes. If you
-enable :ref:`write-blocking <c2c-write-blocking>`:
-
+destination cluster to convert indexes and finalize the changes. By default, 
+``commit`` operations have no effect on writes unless you enable 
+:ref:`write-blocking <c2c-write-blocking>`. If you enable write blocking:
 
 - ``commit`` blocks writes on the source cluster. 
 - ``commit`` blocks writes on the destination cluster until
   ``mongosync`` begins index validation.
 
-
-To monitor the ``commit`` process, use the :ref:`progress
-<c2c-api-progress>` command:
+The ``commit`` operation should take less than a few minutes. To monitor the 
+``commit`` process, use the :ref:`progress <c2c-api-progress>` command:
 
 - The destination cluster is writable when ``canWrite`` is true.
 - Index conversion is complete when ``mongosync`` enters the