Document the -v and --no-color options.

R=iannucci@chromium.org

Change-Id: I07624403f591b23cc5701aa8201124fdfdb65781
Reviewed-on: https://chromium-review.googlesource.com/c/1360710Reviewed-by: Robbie Iannucci <iannucci@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>