title: Facebook login with multiple domains
body: <p>I know that facebook allow me to specify multiple domains for my app.
  <img src="https://i.stack.imgur.com/ghSQ3.png" alt="I can specify multiple App Domains"></p>
  
  <p>But in the "Website with Facebook Login" i can only specify one url.
  <img src="https://i.stack.imgur.com/OPaaJ.png" alt="I can only specify one Site URL"></p>
  
  <p>Is it possible for me, to authenticate users on domain.se, domain.dk and domain.net with the same App ? Or should i still create one app, for each domain ?</p>