add spacing

Author: caitlindavey

source/reference/crud-operations.txt

@@ -289,6 +289,7 @@ when querying and their corresponding methods as examples.
        The information returned by the server for the ``explain`` command 
        varies with server version and deployment topology. The driver's
        ``explain`` method returns whatever the server provided.
+       
        **The return value of ``explain`` method is not part of the driver's
        public API and depends on the server version and deployment topology.**