Bug 1887623: Mention OVS on the About OVN-K page

Author: Mike McKiernan

networking/ovn_kubernetes_network_provider/about-ovn-kubernetes.adoc

@@ -7,8 +7,12 @@ toc::[]
 
 The {product-title} cluster uses a virtualized network for pod and service networks.
 The OVN-Kubernetes Container Network Interface (CNI) plug-in is a network provider for the default cluster network.
+OVN-Kubernetes is based on Open Virtual Network (OVN) and provides an overlay-based networking implementation.
+A cluster that uses the OVN-Kubernetes network provider also runs Open vSwitch (OVS) on each node.
+OVN configures OVS on each node to implement the declared network configuration.
 
 include::modules/nw-ovn-kubernetes-features.adoc[leveloffset=+1]
+
 include::modules/nw-ovn-kubernetes-matrix.adoc[leveloffset=+1]
 // This is a moving target; what is included isn't valid for 4.6
 //include::modules/nw-ovn-kubernetes-metrics.adoc[leveloffset=+1]