docs: use Apache-2.0 WITH LLVM-exception badge

README.md

@@ -133,6 +133,7 @@ cmake --build build -j 8
 This way, all the functionalities are executed on A100 GPUs. For installation, details are provided in the [documentation](https://kokkosfft.readthedocs.io/en/latest/intro/building.html#install-kokkosfft-as-a-library).
 
 ## LICENCE
-[![License](https://img.shields.io/badge/License-Apache_2.0-blue.svg)](https://opensource.org/licenses/Apache-2.0)
+[![License](https://img.shields.io/badge/License-Apache--2.0_WITH_LLVM--exception-blue)](https://spdx.org/licenses/LLVM-exception.html)
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
+
 Kokkos-FFT is distributed under either the MIT license, or at your option, the Apache-2.0 licence with LLVM exception.