add whastnew-2.1 latesturl for the future

Author: mmerickel

docs/conf.py

@@ -140,6 +140,7 @@ def nothing(*arg):
 #     'whatsnew-1.9': 'index',
 #     'whatsnew-1.10': 'index',
 #     'whatsnew-2.0': 'index',
+#     'whatsnew-2.1': 'index',
 #     'tutorials/gae/index': 'index',
 #     'api/chameleon_text': 'api',
 #     'api/chameleon_zpt': 'api',