docs(nix): use real flake namespace example

docs/nix.md

@@ -16,17 +16,29 @@ Use `flake.mk<Name>` for assembly functions passed through module arguments.
 Avoid:
 
 ```nix
-{
-  lib = projectFunctions;
-}
+specialArgs = {
+  lib = flakeLib;
+};
 ```
 
 Use:
 
+```nix
+specialArgs = {
+  inherit flake;
+};
+```
+
+Then call project functions through `flake` inside modules:
+
 ```nix
 {
-  lib = nixpkgs.lib;
-  flake.lib = projectFunctions;
+  flake,
+  lib,
+  ...
+}:
+{
+  networking.networkmanager.unmanaged = [ "interface-name:${flake.lib.bridgeName 10}" ];
 }
 ```