Update License

Author: jgray-19

README.md

@@ -91,10 +91,10 @@ Bug reports, feature requests, and pull requests are encouraged.
 
 ## 📜 License
 
-PyMAD-NG is licensed under the [MIT License](https://github.com/MethodicalAcceleratorDesign/MAD-NG.py/blob/main/LICENSE).
+PyMAD-NG is licensed under the [GNU General Public License v3.0](https://github.com/MethodicalAcceleratorDesign/MAD-NG.py/blob/main/LICENSE).
 
 ---
 
 ## 🙌 Acknowledgements
 
-Built on top of MAD-NG, developed at CERN. This interface aims to bring MAD's power to the Python ecosystem with minimal friction.
+Built on top of MAD-NG, developed at CERN. This interface aims to bring MAD's power to the Python ecosystem with minimal friction.