COMPMID-556 Fix Channel Extract documentation

Change-Id: Iac5fd0800953f6db040f025313e5077fcad74af6
Reviewed-on: https://eu-gerrit-1.euhpc.arm.com/112931
Reviewed-by: Anthony Barbier <anthony.barbier@arm.com>
Tested-by: Anthony Barbier <anthony.barbier@arm.com>
3 files changed