added darwin config

hosts/dadarwin/configuration.nix

@@ -0,0 +1,32 @@
+{ pkgs, ... }: {
+      # List packages installed in system profile. To search by name, run:
+      # $ nix-env -qaP | grep wget
+      environment.systemPackages =
+        [
+          pkgs.neovim
+          pkgs.kitty
+          pkgs.kittysay
+        ];
+
+      programs.direnv.enable = true;
+      # Auto upgrade nix package and the daemon service.
+      services.nix-daemon.enable = true;
+      # nix.package = pkgs.nix;
+
+      # Necessary for using flakes on this system.
+      nix.settings.experimental-features = "nix-command flakes";
+
+      # Create /etc/zshrc that loads the nix-darwin environment.
+      programs.zsh.enable = true;  # default shell on catalina
+      # programs.fish.enable = true;
+
+      # Set Git commit hash for darwin-version.
+      system.configurationRevision = self.rev or self.dirtyRev or null;
+
+      # Used for backwards compatibility, please read the changelog before changing.
+      # $ darwin-rebuild changelog
+      system.stateVersion = 5;
+
+      # The platform the configuration will be used on.
+      nixpkgs.hostPlatform = "x86_64-darwin";
+    }