beamup directories are named after Rust ecosystem properties

[lpil]

# curl --proto '=https' --tlsv1.2 -LsSf https://github.com/tsloughter/beamup/releases/download/v0.6.0/beamup-installer.sh | sh
downloading beamup 0.6.0 aarch64-unknown-linux-gnu
installing to /root/.cargo/bin
  beamup
everything's installed!

To add $HOME/.cargo/bin to your PATH, either restart your shell or run:

    source $HOME/.cargo/env (sh, bash, zsh)
    source $HOME/.cargo/env.fish (fish)

Seeing as this is a BEAM tool I don't think it should have any public references to Rust.

[tsloughter]

Hm, I swear I had a reason it ended up that way despite not originally doing so... I'll need to dig through cargo dist docs again to see if what they support has changed. I'd prefer ~/.local/bin (unless overridden by the user) but I think part of it was I didn't want it to create that dir if it didn't exist, tho maybe that isn't really something I should care about.

Let me look into this again and hopefully improve it in some fashion.