example.com isn't in the default list. Personally, that's okay with me, because I often use it to set up tests.
In general I'd only expect to find in the list only domains that otherwise might be be hosted elsewhere and where setting them up on your server could result in a Denial of Service attack.
I've taken the liberty of uploading the list. you can see it here rather than having to log into your server.
And as the Versions system tells us, you can log in to your system, copy it to the custom subdirectory, and change it to your heart's content.
(note that on your DA system it doesn't have the .txt extension.)
Jeff