Merge branch 'abubakar-bamboo-ci-migration' into 'master'

Bamboo CI Migration documentation

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/133104



Merged-by: Marcel Amirault <mamirault@gitlab.com>
Reviewed-by: Abubakar Siddiq Ango <abubakar@gitlab.com>
Reviewed-by: Marcel Amirault <mamirault@gitlab.com>
Co-authored-by: Abubakar Siddiq Ango <abubakar@gitlab.com>
Co-authored-by: Michael Friedrich <mfriedrich@gitlab.com>