Nix flakes usage

Documentation

nixos wiki docs	https://nixos.wiki/wiki/Flakes
nix run docs	https://nixos.org/manual/nix/unstable/command-ref/new-cli/nix3-run.html

Usage

nix flake show ${PKG}  # show application
nix run        ${PKG}  # run application packaged as a nix-flake