add mastodon validation ref

Author: gitstua

index.html

@@ -100,3 +100,4 @@ <h3 class="post-subtitle">
 </ul>
 {% endif %}
 <a class="twitter-timeline" href="https://twitter.com/cloudy_stuey?ref_src=twsrc%5Etfw" data-tweet-limit="7">Tweets by cloudy_stuey</a> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
+<a rel="me" href="https://aus.social/@cloudy_stuey">Mastodon</a>