Added note

Added note for "TLS Certificates management in Kubernetes"

content/rke/latest/en/cert-mgmt/_index.md

@@ -5,6 +5,8 @@ weight: 150
 
 _Available as of v0.2.0_
 
+> **Note:** This is not "TLS Certificates management in Kubernetes". Refer the [Kubernetes documentation](https://kubernetes.io/docs/tasks/tls/managing-tls-in-a-cluster/) and RKE [cluster.yaml example]({{<baseurl>}}/rke/latest/en/example-yamls/) for more details.
+
 Certificates are an important part of Kubernetes clusters and are used for all Kubernetes cluster components. RKE has a `rke cert` command to help work with certificates.
 
 * [Ability to generate certificate sign requests for the Kubernetes components](#generating-certificate-signing-requests-csrs-and-keys)
@@ -108,16 +110,3 @@ INFO[0001] [certificates] Generating etcd-zzzzz certificate and key
 INFO[0001] Successfully Deployed state file at [./cluster.rkestate]
 INFO[0001] Rebuilding Kubernetes cluster with rotated certificates
 ```
-
-### Optional settings 
-
-Use [extra_args]({{<baseurl>}}rke/latest/en/config-options/services/services-extras/#extra-args) to enable optional settings of each [services]({{<baseurl>}}/rke/latest/en/config-options/services/) that needs certificates and keys.
-
-For example, to enable [Certificate Management](https://kubernetes.io/docs/tasks/tls/managing-tls-in-a-cluster/), add `cluster-signing-cert-file` & `cluster-signing-key-file` to kube-controller in `cluster.yml` file.
-```
-services:
-  kube-controller: 
-    extra_args: 
-      cluster-signing-cert-file: "/etc/kubernetes/ssl/kube-ca.pem"
-      cluster-signing-key-file: "/etc/kubernetes/ssl/kube-ca-key.pem"
-```