nixos/lavalink: add release note

Author: nanoyaki

nixos/doc/manual/release-notes/rl-2505.section.md

@@ -173,6 +173,8 @@
 
 - [nvidia-gpu](https://github.com/utkuozdemir/nvidia_gpu_exporter), a Prometheus exporter that scrapes `nvidia-smi` for GPU metrics. Available as [services.prometheus.exporters.nvidia-gpu](#opt-services.prometheus.exporters.nvidia-gpu.enable).
 
+- [Lavalink](https://github.com/lavalink-devs/Lavalink), a standalone audio sending node based on Lavaplayer and Koe. Availble as [services.lavalink](#opt-services.lavalink.enable).
+
 - [OpenGamepadUI](https://github.com/ShadowBlip/OpenGamepadUI/), an open source gamepad-native game launcher and overlay for Linux. Available as [programs.opengamepadui](#opt-programs.opengamepadui.enable).
 
 - [InputPlumber](https://github.com/ShadowBlip/InputPlumber/), an open source input router and remapper daemon for Linux. Available as [services.inputplumber](#opt-services.inputplumber.enable).