I found this site from Paradise Valley Community College called the above. A little difficult to understand how to navigate initially, but go to the bottom of the page for the links to different parts of the exhibit. This does explain and show what documentation is, how it works, what it's for, and it has excellent examples. I would like to use it in my classes to better explain and describe documentation.

http://www.pvc.maricopa.edu/tdc/POD/index.html