Update container registry troubleshooting documentation for multi-arch builds

Problem

While testing out multi-arch builds using docker buildx build in a GitLab CI job which pushes to the project's container registry using --push that it makes the container registry UI look funky. One can still docker pull images from the registry as expected, but the UI can't find the digest and report storage consumption as it normally does. The .gitlab-ci.yml used to build & push these images can be found here.

Question

• If the digest field is null could we always assume that its an error related to multi-arch build? Or are there are any other fields by which this can be identified?
  • Answered in #420251 (comment 1495060953)

Solution

• Update documentation with workaround under troubleshooting section.
• With answer to question above, the frontend can be updated to show the link to documentation.