Code review comment for ~cjdc/ubuntu-docker-images/+git/templates:fix-ubuntu-docs

LGTM. Based on our discussions, the only suggestion would be rephrasing the sentence "...might be available..." to "The following tags might not be available in public.ecr.aws/ubuntu/ubuntu, but are available in Canonical's ESM service. They are shown here for completeness." — if that helps clarify the intent to the user. Thanks!