CHANGELOG: Mention LLC coloring feature on Arm

It's definitely worth mentioning as one of the most notable feature on
Arm this release.

Signed-off-by: Michal Orzel <michal.orzel@amd.com>
Acked-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>

CHANGELOG.md

@@ -21,6 +21,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
    - Support for NXP S32G3 Processors Family and NXP LINFlexD UART driver.
    - Basic handling for SCMI requests over SMC using Shared Memory, by allowing
      forwarding the calls to EL3 FW if coming from hwdom.
+   - Support for LLC (Last Level Cache) coloring.
  - On x86:
    - xl suspend/resume subcommands.