diff --git a/docs/examples/grpc/ingress.yaml b/docs/examples/grpc/ingress.yaml
index f03559883..9f7739f92 100644
--- a/docs/examples/grpc/ingress.yaml
+++ b/docs/examples/grpc/ingress.yaml
@@ -16,6 +16,9 @@ spec:
           serviceName: fortune-teller-service
           servicePort: grpc
   tls:
+  # This secret must exist beforehand
+  # The cert must also contain the subj-name fortune-teller.stack.build
+  # https://github.com/kubernetes/ingress-nginx/blob/master/docs/examples/PREREQUISITES.md#tls-certificates
   - secretName: fortune-teller.stack.build
     hosts:
       - fortune-teller.stack.build