fix external link in comment

update link to one that is
accessible by all

TBR=iclelland@google.com
NOTRY=true
Change-Id: Ib8fb6d05779d863641d323311435dbbb5807eeee
Reviewed-on: https://skia-review.googlesource.com/92685
Commit-Queue: Cary Clark <caryclark@skia.org>
Reviewed-by: Cary Clark <caryclark@skia.org>
1 file changed