Merge branch 'docs/update-vulnerability-page' into 'master'

Add description about linking a vulnerability to existing Jira issues

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/131210



Merged-by: Russell Dickenson <rdickenson@gitlab.com>
Approved-by: Russell Dickenson <rdickenson@gitlab.com>
Reviewed-by: Egor <egor.khorolskii@gmail.com>
Reviewed-by: Gregory Havenga <11164960-ghavenga@users.noreply.gitlab.com>
Co-authored-by: Egor <egor.khorolskii@gmail.com>