Add a LICENSE file

[kmturley]

Thanks for the amazing work.

It is common practice to add a LICENSE file to your repo, to make clear you intentions regarding the code.

There is a handy guide here it should take just a couple of minutes to add: https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/licensing-a-repository

Thank-you!