Sell the idea of using the wiki to the developers. You've identified some benefits, share those with the developers. If they can see that they'll get something of value out of it they'll start using it.
Example advantages from What Is a Wiki
- Good for writing down quick ideas or longer ones, giving you more time for formal writing and editing.
- Instantly collaborative without emailing documents, keeping the group in sync.
- Accessible from anywhere with a web connection (if you don't mind writing in web-browser text forms).
- Your archive, because every page revision is kept.
- Exciting, immediate, and empowering--everyone has a say.
