add zotero

Author: christopher.pollin@uni.graz.at

_layouts/default.html

@@ -250,7 +250,6 @@ <h1 class="site-name">
                 class="dropdown-item link-dark"
                 href="https://www.zotero.org/groups/4949308/digedtnt/library"
                 >Literatur (Zotero)</a>
-              >
             </li>
           </ul>
         </li>