angulardart docs are missing some packages

[naomiblack]

The angulardart docs are missing some packages that are explicitly included when we build our docs with docgen. I'm not sure how you'd fix this in an automated way -- perhaps by looking for a config file?

If you look at docs.angulardart.org, for instance, you'll see that your version is missing the di, angular:directives, angular:formatter, and angular:animations libraries.

[adam-singer]

@naomiblack looking for a config file would be an option. Would be nice if docgen could be configuration driven. We don't explicitly include the dependent packages when generating the per package documentation. It would blow up a lot of duplication if we did. Would also be nice if docgen supported interlinking of some sort to package versions. I'm not sure who should own this configuration file and if it should be standard across the pub ecosystem.

di is its own package, so I think we generate a specific documentation set for it. The others angular:directives, angular:formatter, and angular:animations live in the angular package but are not directly referenced in the lib/*.dart files. So by default docgen won't pick them up. #50 is related to this issue.