This technet article says that I should

1. Open IIS Manager and navigate to the level you want to manage.
2. In Features View, double-click HTTP Response Headers.
3. On the HTTP Response Headers page, in the Actions pane, click Set Common Headers.
4. In the Set Common HTTP Response Headers dialog box, select the Enable HTTP keep-alive check box and then click OK.

But I don’t see the “HTTP Response Headers” option in my web application configuration (see image below). What am I doing wrong?