GitLab

Also add some blurb about Chrome OS specific things.

BUG=None.
TEST=read it.

Change-Id: Ia9755c354aee0872f7225695c17a5ebdf08cea54
Reviewed-on: https://chromium-review.googlesource.com/1111747
Commit-Queue: Junichi Uekawa <uekawa@chromium.org>
Reviewed-by: Dan Erat <derat@chromium.org>
Cr-Commit-Position: refs/heads/master@{#572484}