Ask HN: Hosted Documentation Websites

Hi Gang-

I'm looking to create a developer-centric documentation site for a product of mine. The major features I'm looking for are:

1) It is to be reached on a subdomain of my main domain

2) It is to support the hosting of various api docs (different versions and programming languages)

3) It is to have some support for forums/help (though if I host these separately that's fine too I guess)

4) It has support for assets of various types

5) I want to be able to easily map out several tutorials on the site

Anybody out there have recommendations?

Thanks, Nate