Add info about networking

[flozanorht]

State the main CNI (OVNKubernetes or the deprecated OpenShiftSDN, no idea how third-party ones would show up) and the ranges for cluster network (nodes), service, and pod networks (internal SDN). This information is critical for some networking issues, caused by conflicting ranges in large organizations.

[flozanorht]

Verify if the names are consistent between installation YAML and networking operator. I think I saw the name "cluster network" with different meanings in those two resources: in installation, it is the pod network, but in networking operator it is the machine network.