Update Readme to mention AUR package

[hcoggins]

First of all, this is a very cool cli tool!

I noticed that there is a package in the AUR for please-cli (https://aur.archlinux.org/packages/please-cli). I would suggest mentioning that in the documentation in the "Installation" section next to the other installation methods, so that AUR users can install please-cli more easily.

Thanks and keep up the good work!

[wd-c4]

How did you install it on ArchLinux?

[xenia-lang]

I think this can be closed. See the arch section of the README.

[heiderich]

I think AUR would be preferred over the manual installation as in https://github.com/TNG/please-cli/blob/main/README.md?plain=1#L93-L100