Escape trailing underscore to fix docs.

Fixes elastic#108, thanks Lambdanaut!

Author: honzakral

elasticsearch/client/__init__.py

@@ -410,7 +410,7 @@ def search(self, index=None, doc_type=None, body=None, params=None):
  :arg ignore_unavailable: Whether specified concrete indices should be
  ignored when unavailable (missing or closed)
  :arg lowercase_expanded_terms: Specify whether query terms should be lowercased
- :arg from_: Starting offset (default: 0)
+ :arg from\_: Starting offset (default: 0)
  :arg preference: Specify the node or shard the operation should be
  performed on (default: random)
  :arg q: Query in the Lucene query string syntax