Add some prioritized labels, and point out need for hand off

Related to https://gitlab.com/gitlab-com/infrastructure/issues/1833

Can potentially replace https://gitlab.com/gitlab-com/www-gitlab-com/merge_requests/6019

@pcarranza please review; if you agree with this, we would need to actually change some of those label priorities in the infrastructure tracker.

mentioned in issue infrastructure#1833 (closed)

What do SL1 and SL2 stand for?

@pcarranza this is pretty important to disseminate actually, https://about.gitlab.com/handbook/infrastructure/security/#security-priority-labels

I'll add it to the Production Team agenda to make sure everyone is familiar. And the label description can link back to the handbook I suppose.

I moved the labels per this MR, all set.

mentioned in merge request !6019 (merged)

added 1 commit

• fdd157e2 - outages are always unscheduled

Compare with previous version

assigned to @pcarranza

Ready for your second review.

merged

mentioned in commit 0ec43f99