nixos/doc/rl-2505: add notes on Nezha update

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

@@ -76,6 +76,8 @@
 
 - `nodePackages.stackdriver-statsd-backend` has been removed, as the StackDriver service has been discontinued by Google, and therefore the package no longer works.
 
+- `nezha` and its agent `nezha-agent` have been updated to v1, which contains breaking changes. See the [official wiki](https://nezha.wiki/en_US/) for more details.
+
 - the notmuch vim plugin now lives in a separate output of the `notmuch`
   package. Installing `notmuch` will not bring the notmuch vim package anymore,
   add `vimPlugins.notmuch-vim` to your (Neo)vim configuration if you want the