`{
inputs = {
nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
nix-doom-emacs.url = "github:nix-community/nix-doom-emacs";
};

outputs = {
self,
nixpkgs,
nix-doom-emacs,
...
}: {
nixosConfigurations.exampleHost = nixpkgs.lib.nixosSystem rec {
system = "x86_64-linux";
modules = [
{
environment.systemPackages =
let
doom-emacs = nix-doom-emacs.packages.${system}.default.override {
doomPrivateDir = ./doom.d;
};
in [
doom-emacs
];
}
# ...
];
};
};
}`

Do I need to paste this in a flake.nix and use nix build?