Understanding Networking topic content is incomplete

Document URL: https://docs.openshift.com/container-platform/4.5/networking/understanding-networking.html

Section Number and Name: Understanding Networking

Describe the issue: content is incomplete

Suggestions for improvement: Love that we have this top level topic. However, more topics need to be added. Currently it mentions that pods need to talk to each other and describes OCP DNS. But it doesn't mention that all kube clusters require an SDN. It doesn't mention Kube CNII and it doesn't mention anything about cluster ingress or egress. We have detailed content in additional topics. The Undertanding Networking page should have a high level intro to all major elements of OCP networking, with links to the detailed pages.

Additional information: