Add GitHub link to header

Author: selbekk

docusaurus/website/siteConfig.js

@@ -28,6 +28,7 @@ const siteConfig = {
   headerLinks: [
     { doc: 'getting-started', label: 'Getting started' },
     { href: 'https://reactjs.org/community/support.html', label: 'Help' },
+    { href: 'https://www.github.com/facebook/create-react-app', label: 'GitHub' },
   ],
 
   /* path to images for header/footer */