chore: annotate sensitive output variable (terraform-google-modules#1519)

Author: themanifold

examples/simple_autopilot_private/outputs.tf

@@ -35,6 +35,7 @@ output "master_kubernetes_version" {
 }
 
 output "ca_certificate" {
+ sensitive = true
  description = "The cluster ca certificate (base64 encoded)"
  value = module.gke.ca_certificate
 }