Merge branch 'priority-changes' into 'master'

Priority labels and severity labels

See merge request gitlab-org/gitlab-ce!17362

CONTRIBUTING.md

@@ -196,6 +196,17 @@ release. There are two levels of priority labels:
   milestone. If these issues are not done in the current release, they will
   strongly be considered for the next release.
 
+### Severity labels (~S1, ~S2, etc.)
+
+Severity labels help us clearly communicate the impact of a ~bug on users.
+
+| Label | Meaning                                  | Example |
+|-------|------------------------------------------|---------|
+| ~S1   | Feature broken, no workaround            | Unable to create an issue |
+| ~S2   | Feature broken, workaround unacceptable  | Can push commits, but only via the command line |
+| ~S3   | Feature broken, workaround acceptable    | Can create merge requests only from the Merge Requests page, not through the Issue |
+| ~S4   | Cosmetic issue                           | Label colors are incorrect / not being displayed |       
+
 ### Label for community contributors (~"Accepting Merge Requests")
 
 Issues that are beneficial to our users, 'nice to haves', that we currently do