Update License to agpl-3.0-only-linking-exception

AGPL-3.0.txt

@@ -634,7 +634,8 @@ the "copyright" line and a pointer to where the full notice is found.
 
     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, version 3.
+    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

LICENSE.txt

@@ -0,0 +1,24 @@
+steamid.v is distributed under the GNU Affero General Public License (AGPL) Version 3, supplemented by additional permissions:
+
+    Copyright (C) 2022  Philipp Böhm
+
+    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, version 3.
+
+    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/>.
+
+    Additional permission under the GNU Affero GPL version 3 section 7:
+
+    If you modify this program, or any covered work, by linking or
+    combining it with other code, such other code is not for that reason
+    alone subject to any of the requirements of the GNU Affero GPL
+    version 3.
+
+The full AGPL license is available in this directory in the file AGPL-3.0.txt.