Correct blocked SMTP ports for GKE

doc/install/kubernetes/gitlab_chart.md

@@ -112,8 +112,7 @@ If your SMTP server requires authentication make sure to read the section on pro
 your password in the [secrets documentation](https://gitlab.com/charts/gitlab/blob/master/doc/installation/secrets.md#smtp-password).
 You can disable authentication settings with `--set global.smtp.authentication=""`.
 
-If your Kubernetes cluster is on GKE, be aware that SMTP ports [25, 465, and 587
-are blocked](https://cloud.google.com/compute/docs/tutorials/sending-mail/#using_standard_email_ports).
+If your Kubernetes cluster is on GKE, be aware that SMTP port [25 is blocked](https://cloud.google.com/compute/docs/tutorials/sending-mail/#using_standard_email_ports).
 
 ### Deploying the Community Edition