lib.extendMkDerivation: add a release note entry

nixos/doc/manual/release-notes/rl-2411.section.md

@@ -54,6 +54,12 @@
 - [`services.displayManager.ly`](#opt-services.displayManager.ly.enable) is a new module for configuring the display manager [ly](https://github.com/fairyglade/ly),
   a TUI-based replacement for SDDM and LightDM meant for window manager users.
 
+- [`lib.customisation.extendMkDerivation`](https://nixos.org/manual/nixpkgs/unstable#function-library-lib.customisation.extendMkDerivation) and [`lib.customisation.adaptMkDerivation`](https://nixos.org/manual/nixpkgs/unstable#function-library-lib.customisation.adaptMkDerivation) are introduced to bring [fixed-point arguments](https://nixos.org/manual/nixpkgs/unstable#chap-build-helpers-finalAttrs) support (capability to take `(finalAttrs: { ... })`) to arguments aside from `stdenv.mkDerivation`.
+
+  `lib.extendMkDerivation` helps define a new build helper supporting (`(finalAttrs: { ... })`) based on another build helper with such support, while `lib.adaptMkDerivation` helps existing build helpers with arguments unable to pass to the base build helper (usually `stdenv.mkDerivation`) to adopt fixed-point arguments support with slight expression changes.
+
+  See [Nixpkgs Manual chapter *Fixed-point arguments of build helpers*](https://nixos.org/manual/nixpkgs/unstable#chap-build-helpers-finalAttrs) for details.
+
 - `srcOnly` was rewritten to be more readable, have additional warnings in the event that something is probably wrong, use the `stdenv` provided by the derivation, and Noogle-compatible documentation was added.
 
 - The default sound server for most graphical sessions has been switched from PulseAudio to PipeWire.