chore: update HowToApplyALicense.md

Signed-off-by: Grigorii Shartsev <me@shgk.me>

Signed-off-by: Grigorii K. Shartsev <me@shgk.me>

contribute/HowToApplyALicense.md

@@ -9,16 +9,60 @@ Additionally Nextcloud doesn't require a CLA (Contributor License
 Agreement). The copyright belongs to all the individual
 contributors.
 
-If you modify an existing file, please keep the existing license header as
-it is and just add your copyright notice:
+## Apply a license to a new file
 
-````
-@copyright Copyright (c) <year>, <your name> (<your email address>)
-````
+If you create a new file please use a license header
 
-If you create a new file please use this license header:
+#### Frontend source (`.js`, `.ts`, `.css` and etc)
 
+```js
+/**
+ * @copyright Copyright (c) <year>, <your name> (<your email address>)
+ *
+ * @license AGPL-3.0-or-later
+ *
+ * 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/>.
+ *
+ */
 ````
+
+or `.vue` files
+
+```html
+<!--
+  - @copyright Copyright (c) <year>, <your name> (<your email address>)
+  -
+  - @license AGPL-3.0-or-later
+  -
+  - 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/>.
+-->
+```
+
+#### Backend source (`.php`)
+
+```php
 /**
  * @copyright Copyright (c) <year>, <your name> (<your email address>)
  *
@@ -38,8 +82,39 @@ If you create a new file please use this license header:
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  *
  */
+```
+
+## Apply a licence to an existing file
+
+If you modify an existing file, please keep the existing license header as
+it is and just add your copyright notice, for example:
+
+````diff
+/**
+ * @copyright Copyright (c) 2022, Alice (alice@nextcloud.local)
+ * @copyright Copyright (c) 2023, Bob (bob@nextcloud.local)
++* @copyright Copyright (c) <year>, <your name> (<your email address>) 
+ *
+ * @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/>.
+ *
+ */
 ````
 
+## DCO
+
 Additionally we require a Developer Certificate of Origin (DCO), look
 at [CONTRIBUTING.md][contributing] to learn more how to sign your commits.