Add slack link (#436)

* Add slack link

Add slack link to footer and to main "about" page.

Author: FR4NK-W

scionlab/templates/scionlab/base.html

@@ -83,11 +83,12 @@ <h1>{% block content_title %}{% endblock content_title %}</h1>
     <div class="container text-muted mt-4">
       <ul class="list-inline">
         <li class="list-inline-item mr-4"><a href="mailto:[email protected]"><span class="fa fa-envelope"></span> Contact</a></li>
+        <li class="list-inline-item mr-4"><a href="https://join.slack.com/t/scionproto/shared_invite/zt-1gtgkuvk3-vQzq3gPOWOL6T58yu45vXg"><span class="fa fa-slack"></span> SLACK</a></li>
         <li class="list-inline-item mr-4"><a href="https://lists.inf.ethz.ch/mailman/listinfo/scion"><span class="fa fa-users"></span> SCION community mailing list</a></li>
         <li class="list-inline-item mr-4"><a href="https://docs.scionlab.org/">Documentation</a></li>
         <li class="list-inline-item"><a href="https://docs.scionlab.org/content/faq/">FAQ</a></li>
       </ul>
-      <p class="mt-2">&copy; 2020 Network Security Group, ETH Zurich</p>
+      <p class="mt-2">&copy; 2023 Network Security Group, ETH Zurich</p>
     </div>
   </footer>
 </body>

scionlab/templates/scionlab/home.html

@@ -67,7 +67,7 @@ <h4>About SCION</h4>
 </p>
 
 <p>
-Please refer to the <a href="https://www.scion-architecture.net" target="_blank">SCION Architecture</a> main page for more information.
+Please refer to the <a href="https://www.scion-architecture.net" target="_blank">SCION Architecture</a> main page for more general information about SCION and join the <a href="https://join.slack.com/t/scionproto/shared_invite/zt-1gtgkuvk3-vQzq3gPOWOL6T58yu45vXg" target="_blank"><span class="fa fa-slack"></span>slack</a> for the developer discussions.
 </p>