I have started developing a documentation distribution. It is based on the core 'Book' module, and two custom modules which allow to create, edit, import and export simple DocBook documents. Other modules (related to Book) can be used as well. The goal is to include and configure all the needed modules and features, in order to provide a working documentation system out-of-the-box. Right now it is working, but only as a proof of concept. More work needs to be done to get all the details right and to make it really useful and easy.
I have also created a group about it on drupal.org: https://groups.drupal.org/docbookwiki
If you like the idea of building such a distribution and you want to keep in touch and to discuss about it, subscribe at this group. If you could also help with developing and improving it, this would be much better, however you don't have to. Just testing, providing feedback, discussing about features, making suggestions etc. is OK.