You might want to consider taking a look at Gollum . I will tell about my thoughts about Gollum, as my needs sound the same as your requirements. I recently started using Gollum for Rails project documentation, and my experience is still very positive. It was developed by people on Github, but is not tied to the Github service and can be used independently of Github.
This is a very active open source project with many committers. The foundation is Sinatra, and you can easily run it on your personal workstation. I keep the Gollum server on my development machine and directly edit the Markdown files and then view the results on the local Gollum server. This is especially nice if you configure your editor to automatically add updates by pressing a key. When you're ready, you can create a static html site using your Gollum wiki using this project.
Also, since it uses git backstage, there is built-in version control and all the power of git.
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