To amend my earlier statements, a wiki as a platform is not the problem. The problem is putting up a wiki and expecting great documentation to appear, without someone to set up a structure, design, and maintain it. You need a leader.
I can't commit to being the leader just now. I'm happy to help though.
I would write the structure as a dialect and sub-page generators from that. Each page would be a plain text file or a set of files which can be separately edited through a simple web interface.
We might have another good alternative option to the wiki (maybe easier and more flexible): use a github repo for all the documentation pages in makedoc format, and have external export batch script to export them in HTML, PDF or whatever format.
I would be able to write most of the reference documentation, but would probably let the dictionnary be written by the community. The githun repo would allow for everyone to contribute while being filtered by one or several managers.