Add docstring

qutebrowser/commands/keys.py

@@ -233,6 +233,7 @@ class KeyParser(QObject):
     # pylint: disable=unused-argument
     @pyqtSlot(str, str)
     def on_config_changed(self, section, option):
+        """Re-read the config if a keybinding was changed."""
         if section == 'keybind':
             self.read_config()