add safe update process to roadmap
Created by: sqs
Assigned to @tsenart based on the discussion at https://sourcegraph.slack.com/archives/C07KZF47K/p1548268483384600. This PR is the right place to discuss whether this improvement should be prioritized.
I originally created this PR and added it under 3.1, but I decided to move it to the "Future" section to stay focused. If anyone would like to propose doing it for 3.1 because they think it is important and/or easy, make the case here on this PR.