Add link to Inari's video tutorial from homepage

index.html

@@ -39,6 +39,7 @@
         /
         <a href="lib/doc/rgl-tutorial/index.html">RGL Tutorial</a>
       </li>
+      <li><a href="https://www.youtube.com/playlist?list=PL4L18Hhub0qFgLgFmzE4h-FxqemBcvWSW">Video Tutorial</a></li>
     </ul>
 
     <a href="download/index.html" class="btn btn-primary ml-3">