DOCSP-38407 read and write concern info (#203)

Author: ltran-mdb2

source/reference/mongosync.txt

@@ -213,6 +213,18 @@ Write Blocking
 You must enable write-blocking when you start ``mongosync`` if you want
 to use :ref:`reverse synchronization <c2c-api-reverse>` later.
 
+User Permissions
+````````````````
+
+.. include:: /includes/fact-write-blocking-requirement.rst
+
+Permissible Writes
+``````````````````
+
+.. include:: /includes/fact-write-blocking-check.rst
+
+.. include:: /includes/fact-write-blocking-when.rst
+
 Commit
 ~~~~~~
 
@@ -232,18 +244,16 @@ The ``commit`` operation should take less than a few minutes. To monitor the
 - Index conversion is complete when ``mongosync`` enters the
   ``COMMITTED`` state.
 
-User Permissions
-````````````````
-
-.. include:: /includes/fact-write-blocking-requirement.rst
+Read and Write Concern
+~~~~~~~~~~~~~~~~~~~~~~
 
-Permissible Writes
-``````````````````
-
-.. include:: /includes/fact-write-blocking-check.rst
-
-.. include:: /includes/fact-write-blocking-when.rst
+By default, ``mongosync`` sets the read concern level to
+:readconcern:`"majority"` for reads on the source cluster. For writes on
+the destination cluster, ``mongosync`` sets the write concern level to
+:writeconcern:`"majority"` with :ref:`j: true <wc-j>`. 
 
+For more information on read and write concern configuration and
+behavior, see :ref:`read-concern` and :ref:`write-concern`. 
 
 .. _c2c-capped-collections: