mention PATH env-var in download/run guide

[Rudxain]

This improves the "Downloading" guide so that users are aware of PATH, for convenience when running love. It also adds an env-var entry to the glossary

[vercel]

@Rudxain is attempting to deploy a commit to the nyakofox's projects Team on Vercel.

A member of the Team first needs to authorize it.

[NyakoFox]

I worry this'll confuse people more than it helps them. People already have a hard enough time opening a terminal...

[Rudxain]

Also, I think I didn't explain much. The actual explanation has 2 levels of indirection (page -> glossary -> WP). I used the jargon "append" instead of "add to the end", and "directory" instead of "folder address". And I didn't explain how to edit env-vars on W10/W11, but I remember it's easy to search in the Start-Menu (literally "system variables" or something)