fix: style

docs/nixos-with-flakes/nixos-with-flakes-enabled.md

@@ -59,19 +59,22 @@ cat flake.nix
 Referencing this template, create the file `/etc/nixos/flake.nix` and write the configuration content. All subsequent system modifications will be taken over by Nix Flakes. 
 Here's an example of the content:
 
-```nix
+```nix{16}
 {
   description = "A simple NixOS flake";
+
   inputs = {
     # NixOS official package source, using the nixos-23.11 branch here
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.11";
   };
+
   outputs = { self, nixpkgs, ... }@inputs: {
     # Please replace my-nixos with your hostname
     nixosConfigurations.my-nixos = nixpkgs.lib.nixosSystem {
       system = "x86_64-linux";
       modules = [
-        # Import the previous configuration.nix we used, so the old configuration file still takes effect
+        # Import the previous configuration.nix we used,
+        # so the old configuration file still takes effect
         ./configuration.nix
       ];
     };