release to arch linux

Create an action to release to the Arch package repository. There is a [guide](https://wiki.archlinux.org/title/Rust_package_guidelines) on the wiki, as well as other ones not specific to Rust with more detail. We may need to release to the AUR initially. Optionally we could support a `-bin` package that just downloads from the github releases instead of building from source.

Add install instructions to the README.md as well.