Is it possible to generate a package documentation page from scaladoc?

If you look at the output of Scaladoc, you'll see that it lists
documented packages, and if you click on one of those links, you'll be
taken to a pages saying "Scala 2
API Specification", and listing the members of that package. I'd like
to insert documentation into that page, but haven't been able to get
documentation at the start of a package file to appear there. Any
ideas how to do this?

Thanks,
Ken