DOCSP-39211 reverse update (#320)

* DOCSP-39211 reverse update

* Fixes per Ajay

Author: kennethdyer

source/reference/api/reverse.txt

@@ -27,8 +27,11 @@ For example:
   the destination cluster. The source cluster will not accept new
   writes.
 
-In this scenario, you can use the ``reverse`` endpoint to sync writes
-from ``cluster1`` to ``cluster0``.
+In this scenario, you can use the ``reverse`` endpoint to sync
+writes from ``cluster1`` to ``cluster0``, including any writes
+that occurred on ``cluster1`` after ``mongosync`` reached
+``canWrite=true``.  To check the ``canWrite`` status during
+sync, use the :ref:`/progress <c2c-api-progress>` endpoint.
 
 Requirements
 ------------
@@ -44,7 +47,7 @@ To use the ``reverse`` endpoint:
   You cannot update these options after the sync starts.
 - ``mongosync`` must be in the ``COMMITTED`` state.
 - The destination cluster oplog must not roll over between 
-  ``mongosync`` reaching the ``COMMITTED`` state and receiving
+  ``mongosync`` reaching ``canWrite=true`` and receiving
   the ``/reverse`` request.
 - :ref:`index-type-unique` require proper formatting.  Collections with indexes
   initially created on MongoDB 4.2 may not have the proper formatting.