Add Mastodon verification link (#303)

Author: ClemABT

www/layouts/partials/footer.html

@@ -1,5 +1,6 @@
 <small style="float: left">{{ .Params.footer | markdownify }}</small>
 <nav>
+  <a rel="me" href="https://piaille.fr/@ergol">Mastodon</a> |
   <a href="https://github.com/Nuclear-Squid/ErgoL">GitHub</a> |
   <a href="https://discord.gg/5xR5K3nAFX">Discord</a>
 </nav>