update document of elasticsearch backend settings

docs/userguide/configuration.rst

@@ -1057,6 +1057,33 @@ Example configuration
 
 .. _conf-riak-result-backend:
 
+.. setting:: elasticsearch_retry_on_timeout
+
+``elasticsearch_retry_on_timeout``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Default: :const:`False`
+
+Should timeout trigger a retry on different node?
+
+.. setting:: elasticsearch_max_retries
+
+``elasticsearch_max_retries``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Default: 3.
+
+Maximum number of retries before an exception is propagated.
+
+.. setting:: elasticsearch_timeout
+
+``elasticsearch_timeout``
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Default: 10.0 seconds.
+
+Global timeout,used by the elasticsearch result backend.
+
 Riak backend settings
 ---------------------