Add :issue: directive for easy linking to bugs.python.org.
diff --git a/Doc/conf.py b/Doc/conf.py
index f6c08c5..6a45242 100644
--- a/Doc/conf.py
+++ b/Doc/conf.py
@@ -14,7 +14,7 @@
 # ---------------------
 
 extensions = ['sphinx.ext.refcounting', 'sphinx.ext.coverage',
-              'sphinx.ext.doctest']
+              'sphinx.ext.doctest', 'pyspecific']
 templates_path = ['tools/sphinxext']
 
 # General substitutions.