[DOCS] Firewall allow list registry.access.redhat.com must be paired with its signature store access.redhat.com

Document URL:

https://docs.openshift.com/container-platform/4.9/installing/install_config/configuring-firewall.html
https://docs.openshift.com/rosa/rosa_getting_started/rosa-aws-prereqs.html#osd-aws-privatelink-firewall-prerequisites

Describe the issue:

Cannot pull images from registry.access.redhat.com in a firewall environment.

The registry.access.redhat.com is listed on the firewall allow list. This registry uses a signature store hosted on access.redhat.com so they need to be allowed together in order to pull images.

$ cat /etc/containers/registries.d/registry.access.redhat.com.yaml
docker:
registry.access.redhat.com:
sigstore: https://access.redhat.com/webassets/docker/content/sigstore

Also it would be nice to improve the registry.access.redhat.com description, it's a pretty common registry used by several tools and examples (we got this issue with OpenShift Pipelines), so saying odo alone in the description is a bit weird.