title: How to set the app icon using electron-forge package on Mac?
body: <p>Can somebody please tell me the instructions for using a custom icon, when compiling an electron app (on mac) when using <code>electron-forge package</code>? Using <code>--icon</code> gives me an error:</p>
  
  <pre><code>error: unknown option `--icon'
  </code></pre>
  
  <p>What am I missing?</p>