Replace references to docker.hub/io with Quay.io

Brandi commented here, "Docker changes. Docker references are being removed from OpenShift, which means we will need to do a docs scrub for references to docker.hub/io and change them to Quay.io. There is some other Docker content that we will need to review with Adam Kaplan + team to make sure the docs are correct. I will partner with Rolfe on this because it's a fairly large docs set to cover. Timeline unclear, but we should probably start looking into this next sprint. "