Add a "zuul: gated" status badge
Other CI systems have 'badges' that can be put into web locations
related to the repo. They show various quality marks, such as "build:
In Zuul, however, we offer a different option - that your build never
It would be nice to let people add a "gated" badge to their repo similar
to how other systems have status badges. This is a badge that just says
"zuul: gated" in zuul's blue.
Co-Authored-By: Tobias Henkel <firstname.lastname@example.org>