Update footer.html

Author: andrew-codechimp

_includes/footer.html

@@ -16,11 +16,12 @@
 
         <div class="social-links">
             {%- include social.html -%}
+            <ul><li><a rel="me" href="https://mastodon.online/@codechimp">Mastodon</a><svg class="svg-icon"><use xlink:href="/assets/minima-social-icons.svg#mastodon"></use></svg> <span class="username">codechimp</span></a></li></ul>
         </div>
 
         <div class="copyright">
             Copyright © 2022 CodeChimp
         </div>
     </div>
 
-</footer>
+</footer>