Update darwin configuration to use aarch64

machines/zelus/configuration.nix

@@ -0,0 +1,19 @@
+{pkgs, ...}: {
+  nixpkgs.config.allowUnfree = true;
+
+  environment = {variables = {LANG = "en_US.UTF-8";};};
+
+  networking = {hostName = "zelus";};
+
+  # Auto upgrade nix package and the daemon service.
+  services.nix-daemon.enable = true;
+  nix.package = pkgs.nixFlakes;
+
+  programs.zsh = {
+    enable = true;
+    # https://github.com/nix-community/home-manager/issues/108#issuecomment-340397178
+    enableCompletion = false;
+  };
+
+  system.stateVersion = 4;
+}