feat: enhance authenticator script with usage instructions and exit command

Signed-off-by: zhenyus <zhenyus@mathmast.com>

cluster/bin/freeleaps-cluster-authenticator

@@ -22,6 +22,10 @@ AUTO_INSTALL_KUBELOGIN=${AUTO_INSTALL_KUBELOGIN:-true}
 help() {
   echo "Freeleaps Cluster Authenticator (Version: ${VERSION})"
   echo ""
+  echo "This script helps you to authenticate with the freeleaps cluster using your Mathmast account, and setup kubectl."
+  echo "It also provides some useful sub-commands to manage the authentication state."
+  echo "Please ensure this script is only for internal use and not to be shared with anyone."
+  echo ""
   echo "Usage: [environment-option=value] freeleaps-cluster-authenticator <sub-command>"
   echo ""
   echo "Sub Commands:"
@@ -310,6 +314,7 @@ reset_auth() {
 
 exit_dashboard() {
   echo "[RUN_DASHBOARD] Kubernetes dashboard stopped."
+  exit 0
 }
 
 run_dashboard() {