It seems that the Webmachine chapter is no longer up to date with the current Webmachine version.
Let’s look at the two most important files, dispatch.conf and hello_resource.erl.
Apparently, dispatch.conf was not 20th century compliant, see https://github.com/basho/webmachine/commit/fd3070fcba70adb7993f36add08760337470b57f
Anyway, thanks for this great book!
EDIT: the resources are now dispatched from hello_config.erl. See here