docs(nix): use host forwarding example

docs/nix.md

@@ -131,22 +131,22 @@ Use:
 
 ### Use `@` for forwarding wrappers
 
-Use `@` when a wrapper passes the complete argument set to another module function.
+Use `@` when a wrapper passes its complete argument set to another function.
 Name each argument the wrapper uses before `...`.
 Forward the bound argument set unchanged.
 
 Avoid:
 
 ```nix
-{ dotfiles, ... }:
-dotfiles.guest { name = "sample"; } { inherit dotfiles; }
+{ hostName, system ? "x86_64-linux", ... }:
+mkHost { inherit hostName system; }
 ```
 
 Use:
 
 ```nix
-args@{ dotfiles, ... }:
-dotfiles.guest { name = "sample"; } args
+args@{ hostName, ... }:
+mkHost args
 ```
 
 ## `let` Bindings