Revert "Revert "Remove nonworking saythanks.io link""

saythanks.io does not work again and the link is now removed.
This reverts commit b2acbcf0e0.

docs/_templates/layout.html

@@ -51,9 +51,6 @@
         <li class="nav-item">
           <a target="_blank" class="nav-link" href="https://github.com/instaloader/instaloader">GitHub</a>
         </li>
-        <li class="nav-item d-sm-none d-lg-block">
-          <a target="_blank" class="nav-link" href="https://saythanks.io/to/aandergr">Say Thanks!</a>
-        </li>
       </ul>
       <form class="form-inline" action="search.html" method="get">
         <div class="input-group my-2 my-sm-0 ml-2">