Fix bulk insert docs (elastic#832)

Author: alysivji

docs/helpers.rst

@@ -83,10 +83,11 @@ document is like ``{"word": "<myword>"}``.
  for word in mywords:
  yield {
  "_index": "mywords",
- "doc": {"word": myword},
+ "_type": "document",
+ "doc": {"word": word},
  }
 
- bulk(es, gendata)
+ bulk(es, gendata())
 
 
 For a more complete and complex example please take a look at