Content Store Documenter is the correct module to use to create the documentation.
Using the portal tree you there are two ways to find all of the objects that are built off of a package. First option is to right click on the package and choose the option “Find related reports” and the 2nd option is to select the built in searches dropdown (to the right of the search box) and choose the search “All objects built off of a package”. Both will return all of the reports that were built off of the model in that package, no matter where the reports are located in the content store.
However this will not find objects that don’t relate directly to the package, for example shortcuts are not built off of a package.