OCPBUGS-38977: Added a limitation for disabling IPv6 OVNK

Author: dfitzmau

modules/nw-ovn-kuberentes-limitations.adoc

@@ -8,6 +8,8 @@
 
 The OVN-Kubernetes network plugin has the following limitations:
 
+* If you set the `ipv6.disable` parameter to `1` in the `kernelArgument` section of the `MachineConfig` custom resource (CR) for your cluster, OVN-Kubernetes pods enter a `CrashLoopBackOff` state. Additionally, updating your cluster to a later version of {product-title} fails because the Network Operator is stuck on a `Degraded` state. Red{nbsp}Hat does not support disabling IPv6 adddresses for your cluster so do not set the `ipv6.disable` parameter to `1`.
+
 // The foll limitation is also recorded in the installation section.
 ifndef::microshift[]
 * For clusters configured for dual-stack networking, both IPv4 and IPv6 traffic must use the same network interface as the default gateway.