Improve open-liberty and openliberty/open-liberty pages

https://hub.docker.com/_/open-liberty is the "Docker Official Images" page for Open Liberty and shows the Ubuntu-based images for Open Liberty while https://hub.docker.com/r/openliberty/open-liberty lists the UBI-based images.

If users aren't familiar, didn't read the details or miss them, users can easily miss what's available, where to find them and what Open Liberty has to offer.

Great if as soon as users land on these pages, clear and consistent information is provided on what container images Open Liberty provides through Docker Hub and how they can get started right away (particularly on the "Docker Official Images" page). The pages can cross reference/link each other if appropriate but preferably, users don't have to traverse multiple spots to find what they need. Considerations should be given to common/popular images first.

(What's on ci.docker README can be updated accordingly too -- Showing what users need to do get going right away highlighting common/popular images before additional/advanced information.)

Cc @Emily-Jiang @gcharters @NottyCode @lauracowen

Review the Docker Hub pages for open-liberty and openliberty/open-liberty, then inspect the ci.docker README to identify where image guidance is presented. Update the relevant documentation so common images, available Ubuntu- and UBI-based options, and immediate getting-started steps are clear and consistent, with links between pages where useful.