title: documentation for ejabberd hooks?
body: <p><a href="https://github.com/esl/MongooseIM/wiki/hooks-and-handlers">Hooks</a> seem to be pretty handy to extend the funcionality of ejabberd.</p>
  
  <p>There are bunch of <a href="https://www.process-one.net/en/wiki/ejabberd_events_and_hooks/">ejabberd hooks</a> mentioned by the makers,but it difficult to understand which one is to be used when,apart from few.</p>
  
  <p>can anybody share some details from their experiences that explains what a particular hook does?</p>