Add: install guide for archlinux users from AUR

[z00rat]

What is the purpose of this pull request? (put an "X" next to item)

[x] Documentation update
[ ] Bug fix
[ ] New feature
[ ] Other, please explain:

What changes did you make? (Give an overview)
i edited the readme file to add instruction for installing this app/package from AUR(arch user repository).
which i maintain there.

package link in AUR: https://aur.archlinux.org/packages/webtorrent-bittorrent-tracker
my user in AUR: https://aur.archlinux.org/account/zoorat
more about AUR: https://wiki.archlinux.org/title/Arch_User_Repository

Which issue (if any) does this pull request address?
none.

Is there anything you'd like reviewers to focus on?
not sure if its allowed but,
by adding this it will be easier for any archlinux user to install, update and maintain this package.

[welcome]

🙌 Thanks for opening this pull request! You're awesome.

[DiegoRBaquero]

Thank for you sharing!

Sadly, the npm package is and will be the only trusted and endorsed repo

[z00rat]

Thank for you sharing!

Sadly, the npm package is and will be the only trusted and endorsed repo

got it.