orgamanager join link and github link added (#8)

Author: nityanandagohain

index.html

@@ -42,9 +42,10 @@
   <!-- Bottom bar -->
   <section class="bottom-bar">
     <ul>
-      <li><a href="https://t.me/yogdaan">Telegram</a></li>
-      <li><a href="https://gitter.im/yogdaan/Lobby">Gitter</a></li>
-      <li><a href="https://orgmanager.miguelpiedrafita.com/join/38074740">Github</a></li>
+      <li><a href="https://orgmanager.miguelpiedrafita.com/join/38074740" target="_blank">Join Us</a></li>
+      <li><a href="https://t.me/yogdaan" target="_blank">Telegram</a></li>
+      <li><a href="https://gitter.im/yogdaan/Lobby" target="_blank">Gitter</a></li>
+      <li><a href="https://github.com/yogdaan" target="_blank">Github</a></li>
     </ul>
   </section>
   <script src='http://cdnjs.cloudflare.com/ajax/libs/jquery/2.1.3/jquery.min.js'></script>