Yes, I do believe you can. That is what the documentation is for generally for anyways (the user). Much like purchasing a product from a store, you would hope the product comes with some kind of documentation on how to use it. You might be a cpanel expert, however your clients may not have a clue to what it is.
Just remember that this in not a support forum for your customers. You should clearly state that the documentation is a "HOW TO" Guide and CPANEL is not the means of support for thier sites. I know most people do not do this intentionally, but when you fail to state the purpose of the documentation and/or to provide a link to your support area this is what happens. This does not do either party any good.
FYI there is a couple of companies out there that have made good solutions for cpanel documentation. They are a lot more user friendly and some can be branded easily.
One is:
http://www.demodemo.com