As your amount of documentation increases, you're forced to come up with a strategy for storing, structuring and reusing it in a clever way.
An increasingly popular solution for reuse is single sourcing that lets you produce different documents in various formats based on the same snippets of information. To this end I have extensive experience with XML and XSLT related technologies and I know how to deploy them in a meaningful way.
I'll give you sound, independent advice on what could work for you, and help you with the implementation - you don't always need the biggest and most expensive system out there.