I've chosen GitBook as my publishing medium because it has an intuitive distribution mechanism (git! and the editor is super easy to use), integrates with GitHub where I have an account, and because it's almost Wiki like in that I can make my changes, if I need to I can revert them, or branch the content - whatever is necessary :-) I can also accept pull requests on GitHub, if anyone so desires. GitBook also has a minimal and intutive design that doesn't get in the way of the subject matter.