docs: add Helm chart 'dns.clusterIP' value. (#5845)

website/source/docs/platform/k8s/helm.html.md

@@ -238,6 +238,8 @@ and consider if they're appropriate for your deployment.
 
   * <a name="v-dns-enabled" href="#v-dns-enabled">`enabled`</a> (`boolean: global.enabled`) - If true, a `consul-dns` service will be created that exposes port 53 for TCP and UDP to the running Consul agents (servers and clients). This can then be used to [configure kube-dns](/docs/platform/k8s/dns.html). The Helm chart _does not_ automatically configure kube-dns.
 
+  * <a name="v-dns-clusterip" href="#v-dns-clusterip">`clusterIP`</a> (`string`) - If defined, this value configures the cluster IP of the DNS service.
+
 * <a name="v-synccatalog" href="#v-synccatalog">`syncCatalog`</a> - Values that configure the [service sync](/docs/platform/k8s/service-sync.html) process.
 
   * <a name="v-synccatalog-enabled" href="#v-synccatalog-enabled">`enabled`</a> (`boolean: false`) - If true, the chart will install all the resources necessary for the catalog sync process to run.