Add formatter to flake.nix

Author: fzakaria

flake.nix

@@ -154,6 +154,10 @@
       };
       version = builtins.substring 0 8 self.lastModifiedDate;
     in {
+      # Formatter for your nix files, available through 'nix fmt'
+      # Other options beside 'alejandra' include 'nixpkgs-fmt'
+      formatter = pkgs.alejandra;
+
       packages = rec {
         tclipd = pkgs.buildGoApplication {
           pname = "tclipd";