COMPMID-741 - Changelog for major release 17.12

Change-Id: If71190e398217ca6ca44df822554998d047b79db
Reviewed-on: https://eu-gerrit-1.euhpc.arm.com/112716
Reviewed-by: Anthony Barbier <anthony.barbier@arm.com>
Tested-by: BSG Visual Compute Jenkins server to access repositories on http://mpd-gerrit.cambridge.arm.com <bsgcomp@arm.com>
6 files changed