This crate works on stable now

[Follpvosten]

I've just checked, and since proc macros were stabilized with the 2018 edition, this crate has been working on stable, so maybe the note about having to use nightly should be removed from the README?

I could open a PR for that, but it's a really minor change, so I don't know if I should.

[bytesnake]

Thanks, removed the information :)