Resolve "quality/triage-ops/lib/devops_labels.rb:378:in `current_stage_name': undefined method `delete_prefix' for "Quality":String (NoMethodError)"

Consider adding documentation to the handbook pages for Triage Operations when creating a new triage policy or triage package:

• https://gitlab.com/gitlab-com/www-gitlab-com/blob/master/source/handbook/engineering/quality/guidelines/triage-operations/index.html.md

Closes #210 (closed)