Ways to put online API documentation using rails

Hey mates!

Currently I am building server data storage for mobile application with can be accessed via rest API.

I am looking for some kind or ready2go software, which allows to produce documentation in Parse Platform style.

Ideally, I'd like to store documentation in markdown and process it into HTML.

I already took a look to nanoc. The problem is that I want to embed documentation inside rails app, not to build stand alone static website like https://docs.recurly.com/

Any ideas?