add AGPL

module.nix

@@ -1,3 +1,20 @@
+# This file is part of birdtown-visit-counter, and is © 2024 Alexander Khodyrev.
+#
+# Full source code is available at https://git.akho.name/akho/birdtown-visit-counter
+#
+# birdtown-visit-counter 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.
+#
+# birdtown-visit-counter 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 birdtown-visit-counter. If not, see <https://www.gnu.org/licenses/>.
+
 inputs:
 { config, lib, pkgs, ... }:
 let