Merge branch 'docs-kramdown-warnings' into 'master'

Fix kramdown warnings in the docs

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/145110



Merged-by: Russell Dickenson <rdickenson@gitlab.com>
Approved-by: Russell Dickenson <rdickenson@gitlab.com>
Co-authored-by: Marcel Amirault <mamirault@gitlab.com>