Nix Community Cachix

Need to hit the fkn binary cache when building Emacs in the CCE. Extracted this after running cachix use nix-community, after installing it:

nix:tangle ~/nix/nixos/cachix.nix:mkdirp yes

{ ... }:

{
  nix.settings.substituters = [
    "https://cache.nixos.org/"
    "https://nix-community.cachix.org"
    "https://nix-on-droid.cachix.org"
  ];
  nix.settings.trusted-public-keys = [
    "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
    "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY="
    "nix-on-droid.cachix.org-1:56snoMJTXmDRC1Ei24CmKoUqvHJ9XCp+nidK7qkMQrU="
  ];
}