Add MTTM of security vulnerabilities to the handbook * Dashboard https://app.periscopedata.com/app/gitlab/758795/Appsec-Embedded-Dashboard * Chart https://app.periscopedata.com/app/gitlab/758795/Appsec-Embedded-Dashboard?widget=9960552&udv=0 ## Tasks * [x] Break down MTTM by product groups / stages: https://app.periscopedata.com/app/gitlab/758795/Appsec-Embedded-Dashboard?widget=9960552&udv=0 * [x] Add the product group / stages chart to the handbook * [ ] <s> Account for bugs with no product/group</s> https://gitlab.com/gitlab-com/www-gitlab-com/-/issues/9948#note_466532221 cc @laurence.bierner @kwiebers @lmai1 @davis_townsend