Add Bash script as a "language" option?

[mhwombat]

First of all, I'd like to say this is an excellent tutorial. I've been using NixOS for over a decade, but your tutorial taught me a few new tricks.

For the "select your language" part, it would be nice to have a Bash/sh option. (All the flake would do is write a script.) It helps to focus on bare-bones nix first, and then move onto understanding language-specific stuff. It would also be a good choice for anyone who wants to use a language that doesn't have a flake template yet.