fix: values format of metrics-server extraArgs (#97)

Author: merll

docs/get-started/installation/custom.md

@@ -118,8 +118,7 @@ If your Kubernetes cluster uses untrusted certificates, make sure to set `metric
 apps:
   metrics-server:
     extraArgs:
-      kubelet-insecure-tls: true
-      kubelet-preferred-address-types: InternalIP
+      - --kubelet-insecure-tls=true
 ```
 
 ### Cluster Autoscaler
@@ -142,9 +141,7 @@ cluster:
 # optionally configure metrics-server for kubelet-insecure-tls
 apps:
   metrics-server:
-    extraArgs:
-      kubelet-insecure-tls: true
-      kubelet-preferred-address-types: InternalIP
+    extraArgs: ["--kubelet-insecure-tls=true"]
 # dns is required!
 dns:
   domainFilters: 
@@ -166,4 +163,4 @@ helm repo update
 
 ```bash
 helm install -f values.yaml apl apl/apl
-```
+```