Mention the `/unsubscribe` quick action in triage reports

This MR adds /done (kudos @caalberts) and /unsubscribe to the reports templates so folks can unassign and unsubscribe easier.

Screenshots

Before	After

Action items

• [-] (If applicable) Add documentation to the handbook pages for Triage Operations =>
• (If applicable) Identify the affected groups and how to communicate to them:
  • [-] /cc @person_or_group =>
  • Relevant Slack channels => #triage, #mr-coaching
  • [-] Week-in-review