Feature Request: Is it possible to analyse a subset of stackage?

[chkl]

This might also be interesting for developement, to test changes quickly.

[picnoir]

So far I mostly used the integration test suite to get a end to end validation of my changes. (cabal test integration-tests).

That said, being able to generate the documentation for a subset of the source directory could be handy, especially if we want to generate some Hackage documentation at some point.

I'm a bit unsure about how this would look UI-wise :/

I'd be happy to integrate this feature if someone want to jump on it.