Update - Migrating EC2 Instances to OpenShift Virtualization

[kmcolli]

https://cloud.redhat.com/experts/rosa/ec2-migration-to-rosa/

test on 4.20 + and add an information banner saying "This guide has been validated on OpenShift 4.20. Operator CRD names, API versions, and console paths may differ on other versions." as this doc has https://cloud.redhat.com/experts/rosa/eso/