nixos/release-notes: strongswan updated to 6.0

Author: NickCao

nixos/doc/manual/release-notes/rl-2511.section.md

@@ -296,6 +296,8 @@
 - Potential race conditions in the network setup when using `networking.interfaces` have been fixed by disabling duplicate address detection (DAD)
   for statically configured IPv6 addresses.
 
+- `strongSwan` has been updated to 6.0. See [strongSwan 6.0.0 release notes](https://github.com/strongswan/strongswan/releases/tag/6.0.0) for a complete list of changes.
+
 - `amdgpu` kernel driver overdrive mode can now be enabled by setting [hardware.amdgpu.overdrive.enable](#opt-hardware.amdgpu.overdrive.enable) and customized through [hardware.amdgpu.overdrive.ppfeaturemask](#opt-hardware.amdgpu.overdrive.ppfeaturemask).
   This allows for fine-grained control over the GPU's performance and maybe required by overclocking softwares like Corectrl and Lact. These new options replace old options such as {option}`programs.corectrl.gpuOverclock.enable` and {option}`programs.tuxclocker.enableAMD`.