I guess one thing that nobody seems to have asked is if you have a legal requirement to store history of changes to the doc's?
Whether you do or don't is going to have an impact on what solutions you can consider.
Also a notification mechanism for out of date copies is also a bundle of fun. If engineer A has a copy of a document and engineer B then edits it and commits the changes you want engineer A to be notified that his copy is out of date.
Document control can become a real can of worms quite easily.
Maybe keep the doc's under CVS or SVN and set it up so that emails are generated to whoever has checked out a copy when updates for the same doc. are checked in to the repository?
Edit: I forgot to add don't forget to use the binary switch, e.g. -kb for CVS, when adding the new doc. Otherwise, you will get any sequences of data that happen to match the ascii for keyword strings having the relevant config management data appended thereby corrupting your doc. data.
