Add 50x and 40x to response codes (Event notification

> The subscriber SHALL respond to the event notification with an appropriate HTTP status code. In the case of a successful notification, the subscriber SHALL respond with an any of the response codes indicated below:
HTTP 200 (OK) or 202 (Accepted) response code to indicate a success; otherwise, the subscriber SHALL respond with an HTTP error status code.

replace with

> The subscriber SHALL respond to the event notification with an appropriate HTTP status code. In the case of a successful notification, the subscriber SHALL respond with any of the response codes indicated below:

and add 40x and 50x to the table.