Update Triage Procedure documentation (#501)

* Update status tags section for Triage Procedure

- Add `S-inactive`
- Add `S-experimental`
- Add search link for PRs with no status tags

* Note that most of the Triage Procedure is out of date

* Document current Triage Procedure

* Fix typo in old docs

* Apply suggestions from code review

Co-authored-by: Dylan DPC <dylan.dpc@gmail.com>

* Remove unnecessary bolding

* Remove outdated part of page

* Update based on review comments

Co-authored-by: Dylan DPC <dylan.dpc@gmail.com>

Author: camelid