refactor: rename modules directory to nix

nix/flake-parts/files.nix

@@ -0,0 +1,28 @@
+{
+  inputs,
+  withSystem,
+  lib,
+  config,
+  ...
+}:
+let
+  inherit (builtins) map head;
+  inherit (lib) concatStringsSep;
+  mkListEntry = x: "- [" + x.path_ + "](" + x.path_ + ")";
+  listOfGeneratedFiles = withSystem (head config.systems) (psArgs: psArgs.config.files.files);
+in
+{
+  imports = [ inputs.files.flakeModules.default ];
+  perSystem = psArgs: {
+    make-shells.default.packages = [ psArgs.config.files.writer.drv ];
+  };
+  text.readme.parts."Generated Files" = concatStringsSep "\n" (
+    [
+      "This flake uses the [files flake-parts module](https://flake.parts/options/files.html) to generate documentation."
+
+      "The list of generated files are:"
+
+    ]
+    ++ (map mkListEntry listOfGeneratedFiles)
+  );
+}