[Zope] README.txt Tab

How do I get the README tab to appear in a product? I created a product and it is working great. However, I would like to add the 'README' tab to the product (and if possible to each instance of the product). I looked at other products that have the README tab and looked at the Product.py source code. It appears that I should just be able to put a README.txt file in my product subdirectory and the tab should automagically appear. It doesn't. What do I need to do?