Add NixOS development tip

[cryptix]

This creates a FHS chroot inside which you can run stuff just like on any other linux/unix system without having to package everything for nixos specificly.

It's not as nice as packaging for nixpkgs and there might be a bit too much stuff in the cabalEnv but it get's the job done.

How to use this:

put the shell.nix inside your checkout of cabal-desktop, run nix-shell and start hacking, aka:

cd repo/of/cabal-desktop
wget https://gist.githubusercontent.com/cryptix/9dc8806fe44f266d47f550b23b703ff8/raw/feb8886a6099a501a2ffc9e0574e818947695dca/shell.nix
nix-shell
npm i
npm start

Open to suggestions how to phrase this better on the readme 😅

[cryptix]

Packaging electron bundles is sadly not something nix community is stoked about.. https://discourse.nixos.org/t/rfc-electron-app-built-from-source/936

[cblgh]

thanks @cryptix 🖤