DOCSP-45060-ignorePreExistingNamespaces-incompatibility (#500) (#504)

(cherry picked from commit 239fab9)

Author: ltran-mdb2

source/reference/beta-program/destinationDataHandling.txt

@@ -53,6 +53,9 @@ The following table shows the strings you can set for
        cluster. Ensure your destination namespaces are different from
        those ``mongosync`` replicates from the source cluster.
 
+       ``"ignorePreExistingNamespaces"`` is not compatible with
+       :ref:`c2c-api-reverse`.     
+
 If you omit a ``"destinationDataHandling"`` string, and the destination
 cluster has user data, ``mongosync`` returns an error. Otherwise,
 ``mongosync`` continues the sync operation.