title: Do Angular 5 components need a `-` in the selector?
body: <p>I'm reviewing this <a href="https://www.youtube.com/watch?v=MPjr-AEnWRg&amp;t=2013s" rel="nofollow noreferrer">Angular 5 forms youtube tutorial</a> and in it Sebastian initially has the form selector named <code>app-form01</code>, but he removes the <code>app-</code> portion.  IIUC custom elements are supposed to have the <code>-</code>.  Has this been relaxed?</p>