Give a hint where to find the email settings.

config/gitlab.yml.example

@@ -38,6 +38,8 @@ production: &base
     # Email address of your support contact (default: same as email_from)
     support_email: support@example.com
 
+    # Email server smtp settings are in [a separate file](initializers/smtp_settings.rb.sample).
+
     ## User settings
     default_projects_limit: 10
     # default_can_create_group: false  # default: true