whatsnew/3.4: mention the new enum module, PEP 435

Doc/whatsnew/3.4.rst

@@ -90,7 +90,7 @@ New syntax features:
 
 New library modules:
 
-* None yet.
+* :mod:`enum`: Implementation of the :pep:`435`.
 
 New built-in features:
 
@@ -290,4 +290,4 @@ that may require changes to your code.
   felt to be over-reaching/overloading of that meaning when the source code is
   found but improperly structured. If you were catching ImportError before and
   wish to continue to ignore syntax or decoding issues, catch all three
-  exceptions now.
\ No newline at end of file
+  exceptions now.