Swap some words to get the proper wording for Signature.bind().

pep-0362.txt

@@ -61,7 +61,7 @@ A Signature object has the following structure attributes:
     Return the string representation of the signature as it might
     appear in source code.
 * bind(\*args, \*\*kwargs) -> dict
-    Create a mapping from argument to parameter for the signature (see
+    Create a mapping from parameter to argument for the signature (see
     `Open Issues`_ for question of how to handle tuples).
 
 The Signature object is stored in the ``__signature__`` attribute of