Merge branch 'improve-alt-text' into 'master'

Updated alt text for image in packages/container_registry.md

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/169586



Merged-by: Marcel Amirault <mamirault@gitlab.com>
Approved-by: Marcel Amirault <mamirault@gitlab.com>
Co-authored-by: Enrico Marchelletta <enrico87@gmail.com>