CHANGELOG: document breaking change of runc update

Co-authored-by: lfbzhm <[email protected]>
Signed-off-by: Markus Lehtonen <[email protected]>

Author: marquiz

CHANGELOG.md

@@ -6,6 +6,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Breaking
+
+- runc update no longer allows `--l3-cache-schema` or `--mem-bw-schema` if the
+  original container spec did not include linux.intelRdt. Without intelRdt in
+  the spec, no CLOS (resctrl group) is created for the container, so these
+  options cannot be properly applied. (#4827)
+
 ## [1.3.0] - 2025-04-30
 
 > Mr. President, we must not allow a mine shaft gap!