nextcloud-server/apps/updatenotification/templates/admin.php

<?php
declare(strict_types=1);
/**
 * @copyright (c) 2018 Joas Schilling <coding@schilljs.com>
 *
 * @author Joas Schilling <coding@schilljs.com>
 *
 * This file is licensed under the Affero General Public License version 3 or
 * later. See the COPYING file.
 */
\OCP\Util::addScript('updatenotification', 'updatenotification');
 ?>

<div id="updatenotification"></div>