add attribution

Author: emerbitz

LICENSE

@@ -1,3 +1,17 @@
+gmx-top4py — Copyright (C) 2025 graeter-group
+
+This project includes or is derived from:
+    kimmdy (https://github.com/graeter-group/kimmdy/tree/main)
+    Copyright (C) graeter-group
+    Licensed under the GNU General Public License v3.0 (GPLv3).
+
+This project is licensed under the terms of the GNU General Public License v3.0 (GPLv3).
+
+-----------------------------------------------------------------------
+Below is the full text of the GNU General Public License v3.0 (GPLv3).
+-----------------------------------------------------------------------
+  
+
                     GNU GENERAL PUBLIC LICENSE
                        Version 3, 29 June 2007