This zip file contains some examples on how you might put the Maven Docbkx Plugin to good use. All of the examples are discussed in the User Manual, found here:
http://docbkx-tools.sourceforge.net/docbkx-samples/manual.html
In order to run a build for one of the examples, simply type:
mvn -f [name of the file] [docbkx goal]
..., with [docbkx goal] being one of the plugin's goals (docbkx:generate-html, docbkx:generate-pdf, etc.), and hit enter.