fix mistake in hardware section from readme

Author: Yannic Nevado Hidalgo

Readme.md

@@ -9,7 +9,7 @@ The Cluster runs on an [K8s](https://kubernetes.io/) Cluster which is managed by
 
 * *Projectname:* zalando-postgres
 * *Namespace:* zalando-postgres
-* *3 Nodes*(per Node 4Cores and 8GB RAM)
+* *4 Nodes*(per Node 4Cores and 8GB RAM)
   * master and three worker nodes
 * *Storage Provisioner*: Longhorn
   * Cluster and PVC Snapshots to [minio](https://min.io/)