Update Docker Hub pull stats in README.md

The README.md shows badges for Docker Hub pull stats, but is somewhat misleading since it implies that the counts are per version / tag, whereas they are for all tags. The README.md should be reformatted to move the counter under the global header for the image, not the per version one.

Even better would be to have access to finer grained analytics, which may or may not be possible with our current Docker Hub subscription.

https://docs.docker.com/docker-hub/repos/manage/trusted-content/dsos-program/

Start by reading README.md and the Docker Hub documentation linked in the issue. Check how the pull-stat badges are grouped, then move the all-tags counter under the image's global header; the work is done when the README no longer implies that counts are per version or tag. Treat finer-grained analytics as a separate question requiring confirmation of the current Docker Hub subscription.

Written by the indexing model from the issue text.