[OSDOCS-13017]: Adding missing link to etcd docs

Author: lahinson

scalability_and_performance/recommended-performance-scale-practices/recommended-etcd-practices.adoc

@@ -21,6 +21,7 @@ include::modules/etcd-node-scaling.adoc[leveloffset=+1]
 [role="_additional-resources"]
 .Additional resources
 * link:https://docs.redhat.com/en/documentation/assisted_installer_for_openshift_container_platform/2024/html/installing_openshift_container_platform_with_the_assisted_installer/expanding-the-cluster#adding-hosts-with-the-api_expanding-the-cluster[Adding hosts with the API]
+* link:https://docs.redhat.com/en/documentation/assisted_installer_for_openshift_container_platform/2023/html/assisted_installer_for_openshift_container_platform/expanding-the-cluster#installing-primary-control-plane-node-healthy-cluster_expanding-the-cluster[Installing a primary control plane node on a healthy cluster]
 * link:https://docs.redhat.com/en/documentation/assisted_installer_for_openshift_container_platform/2024/html/installing_openshift_container_platform_with_the_assisted_installer/expanding-the-cluster#installing-control-plane-node-healthy-cluster_expanding-the-cluster[Expanding the cluster]
 * xref:../../backup_and_restore/control_plane_backup_and_restore/disaster_recovery/scenario-2-restoring-cluster-state.adoc#dr-restoring-cluster-state[Restoring to a previous cluster state]