fix(HelpButton): Improvements.

config.js

     // the menu has option to flip the locally seen video for local presentations
     // disableLocalVideoFlip: false
 
-    // If specified a 'Help' button will be displayed in the overflow menu with a link to the specified URL for
-    // user documentation.
-    // userDocumentationURL: 'https://docs.example.com/video-meetings.html'
-
-    // URLs meant to be opened in different windows.
+    // Deployment specific URLs.
     // deploymentUrls: {
-    //  // If specified a 'Download our apps' button will be displayed in the overflow menu with a link
-    //  // to the specified URL for an app download page.
-    //  downloadAppsUrl: 'https://docs.example.com/our-apps.html'
+    //    // If specified a 'Help' button will be displayed in the overflow menu with a link to the specified URL for
+    //    // user documentation.
+    //    userDocumentationURL: 'https://docs.example.com/video-meetings.html',
+    //    // If specified a 'Download our apps' button will be displayed in the overflow menu with a link
+    //    // to the specified URL for an app download page.
+    //    downloadAppsUrl: 'https://docs.example.com/our-apps.html'
     // }
 
     // List of undocumented settings used in jitsi-meet

interface_config.js

         'fodeviceselection', 'hangup', 'profile', 'info', 'chat', 'recording',
         'livestreaming', 'etherpad', 'sharedvideo', 'settings', 'raisehand',
         'videoquality', 'filmstrip', 'invite', 'feedback', 'stats', 'shortcuts',
-        'tileview', 'videobackgroundblur', 'download'
+        'tileview', 'videobackgroundblur', 'download', 'help'
     ],
 
     SETTINGS_SECTIONS: [ 'devices', 'language', 'moderator', 'profile', 'calendar' ],

react/features/toolbox/components/HelpButton.js

  * @returns {Object}
  */
 function _mapStateToProps(state: Object) {
-    const { userDocumentationURL } = state['features/base/config'];
+    const { userDocumentationURL } = state['features/base/config'].deploymentUrls || {};
     const visible = typeof userDocumentationURL === 'string';
 
     return {