add ipv6 limitation

Author: paigecalvert

docs/vendor/embedded-overview.mdx

@@ -137,3 +137,5 @@ Embedded Cluster has the following limitations:
 * **Policy enforcement on Embedded Cluster workloads is not supported**: The Embedded Cluster runs workloads that require higher levels of privilege. If your application installs a policy enforcement engine such as Gatekeeper or Kyverno, ensure that its policies are not enforced in the namespaces used by Embedded Cluster.
 
 * **Installing on STIG- and CIS-hardened OS images is not supported**: Embedded Cluster isn't tested on these images, and issues have arisen when trying to install on them. Embedded Cluster version 2.8.0 and later will install in standard SELinux environments by setting appropriate SELinux file contexts on the bin directory and restoring SELinux contexts for the data directory after creation.
+
+* **Single-stack IPv6 not supported**: Embedded Cluster does not support installations in single-stack IPv6-only environments. Environments that use IPv4 or dual-stack IPv4/IPv6 networking are supported.