added filetype config to nixvim

users/willifan/common/nixvim/default.nix

@@ -7,6 +7,7 @@
   };
 
   imports = [
+    ./filetype.nix
     ./gitsigns.nix
     ./illuminate.nix
     ./lsp.nix

users/willifan/common/nixvim/filetype.nix

@@ -0,0 +1,14 @@
+{ ... }:
+{
+
+  programs.nixvim.files = {
+    "ftplugin/nix.lua" = {
+      opts = {
+        expandtab = true;
+        shiftwidth = 2;
+        tabstop = 2;
+      };
+    };
+  };
+
+}