Update docstring for errorhandler()
diff --git a/flask/app.py b/flask/app.py
index 59c77a1587..68de2b904b 100644
--- a/flask/app.py
+++ b/flask/app.py
@@ -1153,7 +1153,8 @@ def page_not_found(error):
            that do not necessarily have to be a subclass of the
            :class:`~werkzeug.exceptions.HTTPException` class.
 
-        :param code: the code as integer for the handler
+        :param code_or_exception: the code as integer for the handler, or
+                                  an arbitrary exception
         """
         def decorator(f):
             self._register_error_handler(None, code_or_exception, f)

update the `:param` definition for the `errorhandler()` decorator in `app.py`.