Deprecate cgroup v1

Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>

Author: vvoland

content/manuals/engine/release-notes/29.md

@@ -57,6 +57,12 @@ For a full list of pull requests and changes in this release, refer to the relev
 > For 64-bit devices, you can install the Debian arm64 packages.
 > For 32-bit ARMv7 devices, you can use the Debian armhf packages.
 
+> [!WARNING]
+> **cgroup v1 is deprecated.**
+> Support will be maintained for cgroup v1 until at least May 2029, but users are encouraged to migrate to cgroup v2 as soon as possible.
+> Most distributions have already switched to cgroup v2.
+> See [moby#51111](https://github.com/moby/moby/issues/51111) for more information.
+
 ---
 
 %CHANGELOG-PLACEHOLDER%