mod_http_oauth2: Add TODO about disabling password grant Per recommendation in draft-ietf-oauth-security-topics-23 it should at the very least be disabled by default. However since this is used by the Snikket web portal some care needs to be taken not to break this, unless it's already broken by other changes to this module.

Introduction
============

This module checks the IP address of newly registered users against a
DNS block list. If a positive match is found, it gets logged.

Configuration
=============

  Option              Type     Default
  ------------------- -------- ------------
  registration\_rbl   string   *Required*