Merge branch 'jy-sequence-diagrams-duo-workflow' into 'master'

Duo Workflow: Add sequence diagrams for Gitlab.com

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/157255



Merged-by: Dylan Griffith <dyl.griffith@gmail.com>
Approved-by: Dylan Griffith <dyl.griffith@gmail.com>
Co-authored-by: Jessie Young <jessieyoung@gitlab.com>