Add loadBalanced connection option (mongodb#678)

* add loadBalanced connection option

* SA feedback

Author: rachel-mack

source/connection/specify-connection-options/cluster-settings.txt

@@ -75,6 +75,12 @@ String` or :guilabel:`MongoClientSettings` tab to see the options available:
 
            *Default*: ``false``
 
+       * - ``loadBalanced``
+         - boolean
+         - Specifies whether or not the driver is connecting to MongoDB using a load balancer. 
+            
+           *Default*: ``null``
+        
        * - ``srvServiceName``
          - string
          - Specifies the service name of the `SRV resource records