title: Update other model after POST or UPDATE
body: <p>I have a loopback model 'page', and with an admin panel you can post/edit/remove them.
  I also have another model 'updates' that has 1 string. (random value)</p>
  
  <p>I would like that each time something is posted, edited or removed, that the string of the other value changes.</p>
  
  <p>I can create a new function to get data, but I have no idea how to edit (or hook?) an existing buildin function to update another model.</p>
  
  <p>API example:
  if there is an call: POST: /pages
  then there should be an UPDATE: /updates</p>