quay-v3.4.0 docs need update to correctly registry and image names

w/ 3.4.0 moving from quay.io to RHCC, the docs need to be updated appropriately.

Suggest using variable names from `modules/attributes.adoc`. The variable `productrepo` already exists but names for each of our images should be added (quay, clair, quay-builder, and quay-builder-qemu)

Release notes should indicate change in source and required auto to pull