title: Under maintenance page if Heroku goes down
body: <p>I am using Heroku and I am worried that if it goes down, I want to inform the users.</p>
  
  <p>Where should I place my static <code>under_maintenance.html</code> page, so that I can tell Heroku to point there if the status of the app is under maintenance?</p>
  
  <p>Thanks</p>