Update links to TW team handbook page - code

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/138730



Merged-by: David Dieulivol <ddieulivol@gitlab.com>
Approved-by: Stan Hu <stanhu@gmail.com>
Approved-by: Suzanne Selhorn <sselhorn@gitlab.com>
Approved-by: David Dieulivol <ddieulivol@gitlab.com>
Co-authored-by: Marcel Amirault <mamirault@gitlab.com>