OSDOCS-2831: OVNK and gatewayConfig
OSDOCS-2831: OVNK and gatewayConfig

* Enable customers to route egress traffic
to the host network (and kernel routing table)
for highly-specialized installations and applications.

Ack `runtime` terminology from Surya, but also
use the `post-installation` terminology that the
doc uses.

Mention the hw offload interaction.  Chris T is
covering the doc for that.
Term: Open vSwitch hardware offloading, hopefully
it sticks.

OSDOCS-2831: Adding note about workload disruption to #40293

vikram-redhat/openshift-docs,vikram-redhat/openshift-docs,vikram-redhat/openshift-docs,vikram-redhat/openshift-docs,vikram-redhat/openshift-docs