GitLab

Add instructions for how to use shorthand to set variant's summary
attribute.

Change-Id: I5233dadd21c60f5c354e70d814f613e5f1f8c27c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2388911
Auto-Submit: Weilun Shi <sweilun@chromium.org>
Commit-Queue: Steven Holte <holte@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Cr-Commit-Position: refs/heads/master@{#803943}