This documentation is not using the current rendering mechanism and is probably outdated. The extension maintainer should switch to the new system. Details on how to use the rendering mechanism can be found here.
What does it do?¶
This Extension will replace the BaseUrl to your assets (like Images, CSS-Files and more), to a Domain configured by you.
could be rewritten to: server1.myCDN.com/fileadmin/stuff/image1.jpg