add single stack restriction for IBM Z

Author: SNiemann15

modules/nw-ovn-kubernetes-matrix.adoc

@@ -24,7 +24,7 @@ ifeval::["{context}" == "about-ovn-kubernetes"]
 
 |IPsec encryption for intra-cluster communication|Supported|Not supported
 
-|IPv6|Supported ^[3]^|Not supported
+|IPv6|Supported ^[3]^ ^[4]^|Not supported
 
 |Kubernetes network policy|Supported|Supported
 
@@ -47,7 +47,7 @@ ifeval::["{context}" == "about-openshift-sdn"]
 
 |IPsec encryption|Not supported|Supported
 
-|IPv6|Not supported|Supported ^[3]^
+|IPv6|Not supported|Supported ^[3]^ ^[4]^
 
 |Kubernetes network policy|Supported|Supported
 
@@ -64,5 +64,7 @@ endif::[]
 
 2. Egress router for OVN-Kubernetes supports only redirect mode.
 
-3. IPv6 is supported only on bare metal, vSphere, IBM Power, and {ibmzProductName} clusters.
+3. IPv6 is supported only on bare metal, vSphere, {ibmpowerProductName}, and {ibmzProductName} clusters.
+
+4. IPv6 single stack is not supported on {ibmpowerProductName} and {ibmzProductName} clusters.
 --