whatsnew: Add PEP 478.
diff --git a/Doc/whatsnew/3.5.rst b/Doc/whatsnew/3.5.rst
index 4530a13..8ac44a0 100644
--- a/Doc/whatsnew/3.5.rst
+++ b/Doc/whatsnew/3.5.rst
@@ -56,7 +56,7 @@
 
 .. seealso::
 
-    .. :pep:`4XX` - Python 3.5 Release Schedule
+    :pep:`478` - Python 3.5 Release Schedule
 
 
 Summary -- Release highlights