fix order of arguments in documentation for client's get method

Author: keith pinto

elasticsearch/client/__init__.py

@@ -333,9 +333,9 @@ def get(self, index, id, doc_type='_all', params=None):
  `<http://www.elastic.co/guide/en/elasticsearch/reference/current/docs-get.html>`_
 
  :arg index: The name of the index
+ :arg id: The document ID
  :arg doc_type: The type of the document (use `_all` to fetch the first
  document matching the ID across all types)
- :arg id: The document ID
  :arg _source: True or false to return the _source field or not, or a
  list of fields to return
  :arg _source_exclude: A list of fields to exclude from the returned