allow naming output dir

[brainlessbitch]

just being able to name the output dir, i wanna have it be called tsuki.nvim, but the actual plugin to be called tsuki (i also already have a dir called tsuki so i can't really use that name for the dir)

[titaniumtraveler]

This PR should solve that: #13
Though it might still take a bit until it is accepted.
(The maintainer is pretty busy currently.)

[titaniumtraveler]

Was merged now!