text: Title: When view_closed event is unhandled, bolt logs out incorrect suggestion on how to handle the event.
  Body: If you open a view in a bolt-py app, and set `notify_on_close=True` on this view, and have a view_submission event handler but _not_ a view_closed handler, Bolt will log out a warning and suggestion:
  
  ```
  WARNING:slack_bolt.App:Unhandled request ({'type': 'view_closed', 'view': {'type': 'modal', 'callback_id': 'message_actions_modal'}})
  ---
  [Suggestion] You can handle this type of event with the following listener function:
  
  @app.view("message_actions_modal")
  def handle_view_events(ack, body, logger):
      ack()
      logger.info(body)
  ```
  
  The suggestion is incorrect to handle the view_closed event. The decorator is incorrect (it should be `@app.view_closed` instead of `@app.view`).