Update the nixos-rebuild example to specify --target-host
https://wiki.nixos.org/wiki/Nixos-rebuild
Mention the nix-shell command, which allows running NixOS operations for non-NixOS distros if packages are installed.
https://nix.dev/manual/nix/2.18/command-ref/new-cli/nix3-shell
In the future, there will be a useable workflow to do all this for you whenever Tangled implements dispatch workflows on the frontend, but that's ultimately a separate issue.