Fix #64 - Create LICENSE

[gothicVI]

Fix #64 by adding a license file.

[clefebvre]

That's not specific enough. The README already explains the licenses for the code, the flags and the landing page icons.

[gothicVI]

That's not specific enough. The README already explains the licenses for the code, the flags and the landing page icons.

May I ask in what way this is not specific enough?
License files are the standard way of indicating repository licenses on GitHub as per:
https://docs.github.com/en/free-pro-team@latest/github/creating-cloning-and-archiving-repositories/licensing-a-repository