Mark PEP 487 as Final

Also add the missing Resolution link to Guido's post accepting the PEP.

pep-0487.txt

@@ -3,13 +3,14 @@ Title: Simpler customisation of class creation
 Version: $Revision$
 Last-Modified: $Date$
 Author: Martin Teichmann <lkb.teichmann@gmail.com>,
-Status: Draft
+Status: Final
 Type: Standards Track
 Content-Type: text/x-rst
 Created: 27-Feb-2015
 Python-Version: 3.6
 Post-History: 27-Feb-2015, 5-Feb-2016, 24-Jun-2016, 2-Jul-2016, 13-Jul-2016
 Replaces: 422
+Resolution: https://mail.python.org/pipermail/python-dev/2016-July/145629.html
 
 
 Abstract