Merge pull request #9 from HunterBelanger/move-to-gpl

Changes license to GPLv3+

README.md

@@ -1,7 +1,7 @@
 # Papillon Nuclear Data Library
 [![CMake Workflow](https://github.com/HunterBelanger/papillon-ndl/actions/workflows/cmake.yml/badge.svg)](https://github.com/HunterBelanger/papillon-ndl/actions)
 [![Documentation Status](https://readthedocs.org/projects/papillon-ndl/badge/?version=latest)](https://papillon-ndl.readthedocs.io/en/latest/?badge=latest)
-[![License](https://img.shields.io/badge/License-CeCILL%20v2.1-brightgreen)](https://cecill.info/index.en.html)
+[![License](https://img.shields.io/badge/License-GPLv3-brightgreen)](https://github.com/HunterBelanger/papillon-ndl/blob/develop/LICENSE)
 
 The Papillon Nuclear Data Library (NDL) is a C++/Python library for reading,
 sampling, and interacting with continuous energy nuclear data, stored in the ACE
@@ -12,13 +12,8 @@ the [documentation site](https://papillon-ndl.readthedocs.io). That is where you
 will also be able to fined more detailed installation instructions.
 
 ## License
-PapillonNDL is provided under the terms and conditions of the CeCILLv2.1
-license. This is a French equivalent of the GPLv3 license, and is explicitly
-compatible with both the GPLv2 and v3. The French version of this license is
-provided in the LICENSE file. The equally valid English version may be found
-[here](https://papillon-ndl.readthedocs.io/en/latest/license/english.html).
-The CeCILLv2.1 is approved by the FSF. More information about this license may
-be found [here](https://cecill.info/).
+PapillonNDL is provided under the terms and conditions of the GPLv3
+license.
 
 ## Dependencies
 The library may be built on Unix-like operating systems or on Windows. All that