Thanks for the important question about documentation using the traditional Access tools. The short answer is no, the development environment for Access web apps does not include the tools to which you refer. This is a pain point which we all hope will eventually be addressed by Microsoft.
With regard to the full documentation of the Maid to Order sample web app. I have always thought of the book that way; it described the steps we went through to build it from start to finish. If you follow that process, you'll touch on all of the relevant factors.
However, that doesn't include a relationship diagram (that's not available, and may not ever be provided, I'm afraid.) It would be a wonderful addition to the design surface, though, wouldn't it?