docs: Update on the update in flake-parts template

Author: akirak

README.md

@@ -55,7 +55,9 @@ nix flake init -t github:akirak/flake-templates#flake-utils
 
 ### [flake-parts](flake-parts/flake.nix)
 
-This is a boilerplate based on [flake-parts](https://flake.parts/).
+This is a boilerplate based on [flake-parts](https://flake.parts/). It also
+includes a basic [treefmt-nix](https://github.com/numtide/treefmt-nix)
+configuration, so you can run `nix fmt` and formatting checks out of the box.
 
 ``` bash
 nix flake init -t github:akirak/flake-templates#flake-parts

doc/src/content/docs/patterns/formatting/treefmt-nix.mdoc

@@ -7,8 +7,9 @@ title: Checking formatting using treefmt-nix on GitHub Actions
 This tutorial explains how to check formatting on GitHub Actions using
 [treefmt-nix](https://github.com/numtide/treefmt-nix).
 ## Add a treefmt-nix configuration
-Some of the flake templates, including `treefmt`, integrates treefmt-nix out of
-the box. You don't have to add a configuration in this case.
+Some of the flake templates, including `treefmt` and `flake-parts`, integrate
+treefmt-nix out of the box. You don't have to add a configuration in this
+case.
 
 Otherwise, please add a configuration to your flake manually by consulting [the
 documentation](https://github.com/numtide/treefmt-nix?tab=readme-ov-file#flakes).