Eliminate camelcase function name

Doc/whatsnew/2.6.rst

@@ -515,11 +515,11 @@ fixes.  Here's a partial list of the most notable changes, sorted alphabetically
 by module name. Consult the :file:`Misc/NEWS` file in the source tree for a more
 complete list of changes, or look through the CVS logs for all the details.
 
-* A new data type in the :mod:`collections` module: :class:`NamedTuple(typename,
+* A new data type in the :mod:`collections` module: :class:`named_tuple(typename,
   fieldnames)` is a factory function that creates subclasses of the standard tuple
   whose fields are accessible by name as well as index.  For example::
 
-     >>> var_type = collections.NamedTuple('variable', 
+     >>> var_type = collections.named_tuple('variable', 
      ...             'id name type size')
      # Names are separated by spaces or commas.
      # 'id, name, type, size' would also work.