DOCS-518 document replSetMaintenance command

Author: kay-kim

source/reference/command/replSetMaintenance.txt

@@ -19,7 +19,14 @@ replSetMaintenance
    :dbcommand:`replSetMaintenance` command:
 
    - You cannot run the command on the Primary.
+   
    - You must run the command against the ``admin`` database.
-   - When enabled ``replSetMaintenance: 1``, the member will change state to ``RECOVERING``.
+   
+   - When enabled ``replSetMaintenance: 1``, the member will change
+     state to ``RECOVERING``. While the member is in ``RECOVERING`` state:
+     
+     - The member is not accessible for read operations.
+     
+     - The member continues to sync its :term:`oplog` from the Primary.
 
    .. admin-only