Update footer link from Mastodon to Fosstodon

Author: nbauma109

www/index.html

@@ -210,7 +210,7 @@ <h2>Articles</h2>
 </main>
 
 <footer>
-    <p>© Nicolas Baumann (nbauma109) | Open Source Projects | <a href="https://mastodon.social/@nbauma109" target="_blank" rel="me noopener noreferrer">Mastodon</a></p>
+    <p>© Nicolas Baumann (nbauma109) | Open Source Projects | <a href="https://fosstodon.org/@nbauma109" target="_blank" rel="me noopener noreferrer">Fosstodon</a></p>
 </footer>
 
 </body>