Add more suggestion in the runbook.

Possible root cause:
1) Caused by Network connectivity: bad endpoint, firewall, load balancer, service on the other side down, service overwhelmed and not able to provide the service, etc
2) Caused by authz/authn
3) Identify the issue: get a TCPDUMP inside the collector pod suffering the issue (https://access.redhat.com/solutions/4569211)
4) provide Logging must-gather (https://docs.redhat.com/en/documentation/red_hat_openshift_logging/latest/html/about_openshift_logging/cluster-logging-support#cluster-logging-must-gather-collecting_cluster-logging-support)

For the points 1 and 2, it could be used something like present in https://access.redhat.com/articles/7089751#connectivity