update URL

Author: mtf90

_includes/footer.html

@@ -17,7 +17,7 @@
             </ul>
             <ul class="nav d-block d-md-flex">
                 <li class="nav-item">
-                    <a class="nav-link tu-link" href="http://ls5-www.cs.tu-dortmund.de">
+                    <a class="nav-link tu-link" href="https://ps.cs.tu-dortmund.de">
                         <img style="height: 24px; margin-right: 8px; margin-top: -4px;" src="{{ '/assets/images/tu.png' | relative_url }}" alt="TU Dortmund logo">TU Dortmund University</a>
                 </li>
             </ul>