chore: Add SPDX header

Signed-off-by: Andy Scherzinger <info@andy-scherzinger.de>

src/components/board/BoardSidebar.vue

@@ -1,24 +1,7 @@
 <!--
-  - @copyright Copyright (c) 2018 Julius Härtl <jus@bitgrid.net>
-  -
-  - @author Julius Härtl <jus@bitgrid.net>
-  -
-  - @license GNU AGPL version 3 or any later version
-  -
-  - This program is free software: you can redistribute it and/or modify
-  - it under the terms of the GNU Affero General Public License as
-  - published by the Free Software Foundation, either version 3 of the
-  - License, or (at your option) any later version.
-  -
-  - This program is distributed in the hope that it will be useful,
-  - but WITHOUT ANY WARRANTY; without even the implied warranty of
-  - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-  - GNU Affero General Public License for more details.
-  -
-  - You should have received a copy of the GNU Affero General Public License
-  - along with this program. If not, see <http://www.gnu.org/licenses/>.
-  -
-  -->
+  - SPDX-FileCopyrightText: 2018 Nextcloud GmbH and Nextcloud contributors
+  - SPDX-License-Identifier: AGPL-3.0-or-later
+-->
 
 <template>
 	<NcAppSidebar v-if="board != null"