title: Firebase CLI: "Configure as a single-page app (rewrite all urls to /index.html)"
body: <p>I just used the Firebase CLI to init a static hosting project. What exactly happens when you enable the "configure as a single-page app" option? I'm looking for a description of exactly which files are modified, and what kind of effect this has on the Firebase backend. </p>
  
  <p><a href="https://i.stack.imgur.com/eWIZy.png" rel="noreferrer"><img src="https://i.stack.imgur.com/eWIZy.png" alt="Screenshot of firebase init command"></a></p>