Add license header to README

Author: esensar

README.md

@@ -34,5 +34,13 @@ Quad9 connect uses the following third-party software:
 - [Ensar Sarajčić](https://github.com/esensar) - Developer
 
 ## License
+Quad9 Connect - Android application for Quad9 recursive DNS cybersecurity and privacy services 
+Copyright (C) 2025 Quad9 DNS
+
+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 <https://www.gnu.org/licenses/>.
 
 [AGPL-3.0](./LICENSE)