[Documentation]: Document what `Hit environment` means

[nh2]

Hi, great tool!

#23 (comment) added Nix-Env: Hit environment visible from the command menu.

I didn't understand what Hit means; it seems a bit strange of a terminology for reloading. Running it doesn't show anything visual so that doesn't give the user a hint either.

It would be cool if that command could get a more descriptive name so users understand what it does.