Added link to GitHub in footer

Author: LaurentRDC

templates/footer.html

@@ -46,6 +46,7 @@
         <a href="https://discourse.haskell.org/c/haskell-foundation/11" target="_blank" class="text-4xl block"><span class="fab fa-discourse"></span></a>
         <a rel="me" href="https://mastodon.social/@haskell_foundation" target="_blank" class="text-4xl block"><span class="fab fa-mastodon"></span></a>
         <a href="https://www.youtube.com/@HaskellFoundation" target="_blank" class="text-4xl block"><span class="fab fa-youtube"></span></a>
+        <a href="https://github.com/haskellfoundation" target="_blank" class="text-4xl block"><span class="fab fa-github"></span></a>
       </div>
     </div>