feat: change nix formater from alejandra to nixfmt-rfc-style (#50)

- The recommended nix formatter is nixfmt-rfc-style and not alejandra.

config/plugins/lsp/conform.nix

@@ -106,7 +106,7 @@
             "isort"
           ];
           lua = ["stylua"];
-          nix = ["alejandra"];
+          nix = ["nixfmt-rfc-style"];
           markdown = [
             [
               "prettierd"
@@ -137,6 +137,9 @@
           isort = {
             command = "${lib.getExe pkgs.isort}";
           };
+          nixfmt-rfc-style = {
+            command = "${lib.getExe pkgs.nixfmt-rfc-style}";
+          };
           alejandra = {
             command = "${lib.getExe pkgs.alejandra}";
           };

flake.nix

@@ -44,12 +44,12 @@
             src = ./.;
             hooks = {
               statix.enable = true;
-              alejandra.enable = true;
+              nixfmt-rfc-style.enable = true;
             };
           };
         };
 
-        formatter = pkgs.alejandra;
+        formatter = pkgs.nixfmt-rfc-style;
 
         packages.default = nvim;