12.3 blog update for for issue 40096 -ci_registry_user permissions

Engineer(s): @ggelatti | Product Marketing: @williamchia | Tech Writer: @axil

Content checklist

• YML filled out for feature
• Description is informative and focuses on the problem we're solving and the value we're delivering
• [] Documentation is updated and linked - @ggelatti can we add an example to https://docs.gitlab.com/ee/ci/docker/using_docker_build.html#container-registry-examples
• Screenshot/video is included (optional for secondary items)

Review

When the above is complete and the content is ready for review, it should be reviewed by Product Marketing and Tech Writing:

• PMM review
• Tech writing

Checklist for reference

• Make sure feature description is positive and cheerful
• Check Feature name
• Check Feature availability (Core, Starter, Premium, Ultimate badges)
• Feature is added to data/features.yml (with accompanying screenshots)
• Check all images size < 300KB (compressed, max width 1000 pixels)
• Check that documentation is updated and easy to understand
• Check Documentation links (all feature blocks contain documentation_link)
• Run the content through an automated spelling and grammar check
• Validate all links are functional

References (optional)

• Issue: gitlab-org/gitlab-foss#40096 (closed)
• Release post: