Another option is to create a OneNote notebook in SharePoint and then let your team use that for a lot of their documentation.
- It is synchronized between SharePoint to their local PCs so the content
is available to the team members even when they are offline. Offline updates are sync'd into SharePoint the next time they are online
- OneNote's structure is ideal for quickly evolving documentation as it can be easily restructured
- Multiple people to update the same notebook page at the same time and all updates are kept in sync.
- Whenever content is updated within the Notebook, that page is bolded
for everyone sharing that notebook so anyone can see what has changed
- PDFs can be created either using the SaveAs functionality within
OneNote natively or a third party (like the free open source
Obviously, the complexity of certain design documents require specific products, like Visio, but most of the documentation can be done directly in OneNote.
Another less obvious advantage of using OneNote this way is that all meetings notes (both within the team and with project stakeholders/decision makers) can also be stored there, allowing the whole team to keep up to date with changes as they happen.
I've used this approach on several projects and it has worked out very well.