Update index.html

Author: AionSystem

services/index.html

@@ -258,6 +258,7 @@
     <li><a href="/case-studies/">Case-Studies</a></li>
     <li><a href="/certify/">Certify</a></li>
     <li><a href="/submissions/">Submissions</a></li>
+    <li><a href="/dev-tools/">Dev-Tools</a></li>
     <li><a href="/about/">About</a></li>
   </ul>
 </nav>