Add LICENSE

[notpushkin]

Hey, first of all thanks for your wonderful project!

I've noticed this repo lacks a LICENSE file, which is the usual way of specifying the project's license. This means the project is not licensed / non-open source, and people can't use it legally.

I undertand that stars/memory usage metric might look cool but I think allowing even more people to exit Vim is much more important. Could you pick a license and add it to the repo? Let me know if you need any help with that!

/s