DOCSP-38784: Sharded cluster retries (#570)

Author: norareidy

source/whats-new.txt

@@ -65,6 +65,10 @@ New features of the 5.2 driver release include:
 
       :ref:`java-search-indexes` in the Indexes guide
 
+- When a sharded cluster operation is unsuccessful, the {+driver-short+} avoids selecting
+  the same ``mongos`` server for operation retry attempts if other ``mongos`` servers are
+  available.  
+  
 .. _java-version-5.1.3:
 
 What's New in 5.1.3