Fix string format error while we're in here.

Author: jimrollenhagen

docs/views.rst

@@ -223,7 +223,7 @@ registration code::
         app.add_url_rule(url, defaults={pk: None},
                          view_func=view_func, methods=['GET',])
         app.add_url_rule(url, view_func=view_func, methods=['POST',])
-        app.add_url_rule('%s<%s:%s>' % (url, pk), view_func=view_func,
+        app.add_url_rule('%s<%s:%s>' % (url, pk, pk_type), view_func=view_func,
                          methods=['GET', 'PUT', 'DELETE'])
 
     register_api(UserAPI, 'user_api', '/users/', pk='user_id')