Update index.html with mastodon verification

Author: LinuxJava7

index.html

@@ -124,7 +124,7 @@ <h3>GNOME</h3>
           </a>
         </li>
         <li class="mastodon">
-          <a href="https://mastodon.social/@linuxjava7" title="Mastodon" target="_blank" rel="noopener noreferrer">
+          <a rel="me" href="https://mastodon.social/@linuxjava7" title="Mastodon" target="_blank" rel="noopener noreferrer">
           Mastodon
           </a>
         </li>