feat(HelpOverflowButton): Implement.

interface_config.js

@@ -189,6 +189,12 @@ var interfaceConfig = {
      */
     AUTO_PIN_LATEST_SCREEN_SHARE: 'remote-only'
 
+    /**
+     * The link to the user documentation.
+     */
+    // HELP_LINK: 'https://docs.example.com/video-meetings.html',
+
+
     /**
      * How many columns the tile view can expand to. The respected range is
      * between 1 and 5.