Using the gollum markdown ruby extension
Markdown is the most versatile documentation.
Using the gollum ruby extension, gives you a local web-server (localhost:4567), where you can preview your documentation, before committing, and pushing to Github
There is a problem using Ruby 2.2 with gollum. To install gollum, and resolve this issue (use Ruby 2.2 head):
rvm install ruby-2.2-head
Create a .ruby-version file (in the root of your git repository), which has a single line:
> > ruby-2.2-head > >
gem install gollum gem install github-markdown
gollum http://localhost:4567/ in a web browser
You can write, and preview your markdown, then commit and push to github (gitlab) :D
http://alblue.bandlem.com/2011/05/git-tip-of-week-gollum.html