add note about ahriman to index page

package/share/ahriman/templates/repo-index.jinja2

@@ -85,6 +85,9 @@ SigLevel = Database{% if has_repo_signed %}Required{% else %}Never{% endif %} Pa
                         <li><a class="nav-link" href="{{ homepage }}" title="homepage">homepage</a></li>
                     {% endif %}
                 </ul>
+                <ul class="nav">
+                    <li><a class="nav-link" href="https://github.com/arcan1s/ahriman" title="sources">ahriman</a></li>
+                </ul>
             </footer>
         </div>