Add uninstall instructions

[andrewedstrom]

Hey Luan,

Long time no see—I hope you've been doing well!

It makes a ton of sense that you're deprecating this. Congrats on simplifying your life a little bit!

Would you mind adding a sentence or two to the deprecation notice letting us know how we can uninstall your config and start over with the default vim configuration ourselves?

I assume it's just

rm -rf ~/.config/nvim