nixos/doc/rl-2505: mention timescaledb

Author: kirillrdy

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

@@ -22,6 +22,10 @@
 
 - `buildGoPackage` has been removed. Use `buildGoModule` instead. See the [Go section in the nixpkgs manual](https://nixos.org/manual/nixpkgs/unstable/#sec-language-go) for details.
 
+- `timescaledb` requires manual upgrade steps.
+    After you run ALTER EXTENSION, you must run [this SQL script](https://github.com/timescale/timescaledb-extras/blob/master/utils/2.15.X-fix_hypertable_foreign_keys.sql). For more details, see the following pull requests [#6797](https://github.com/timescale/timescaledb/pull/6797).
+    PostgreSQL 13 is no longer supported in TimescaleDB v2.16.
+
 - `kanata` was updated to v1.7.0, which introduces several breaking changes.
   See the release notes of
   [v1.7.0](https://github.com/jtroo/kanata/releases/tag/v1.7.0)