The upgrading section should mention the need to set spec.serviceAccout, which was not there before. I suggest linking to the section that explains how to set up the "logcollector" user account: https://docs.openshift.com/container-platform/4.17/observability/logging/logging-6.0/log6x-clf.html#legacy-service-accounts
and then instruct the user to add to their CLF:

apiVersion: observability.openshift.io/v1
kind: ClusterLogForwarder
spec:
  serviceAccount: logcollector

    logging 6.0.0

    Doc issue