Actually most of the package do currently have documentation, the same documentation provided by aD when ACS 4.2 was released.
You need to point your browser locally at packages/foo-package/www/doc to find them. The documentation tends to be at the requirements-design level rather than user level, but they should at least help you understand what a package does and how it does it.
As Roberto says we're making progress in our own documentation efforts, which will build on documents inherited from aD. And the more help we get the better the documents will be!
