We are definitely a lot younger than Readme, no denying that ;) We also are approaching the docs with different intent. @gkoberger outlined here their goals. We certainly focus on making the documenting process as easy as possible. You can spend minimal time and still generate very high-quality documentation. So you have no excuse not to document ;)

Hey! ReadMe founder here. I'm always excited to have other companies working on docs :)

I haven't met Ana and Maria yet (hopefully will!), but it does seem like we both agree documentation is incredibly important for APIs. Based on what I've seen, ReadMe thinks about things a bit differently. Our goal isn't to just display all the info about your API, but rather make your API easy to use, debug, etc. Our docs are interactive, know things about your users, etc. We want the docs to be the full UI/UX for your API.

So, tl;dr = similar problem, and hopefully you check us both out :)

(Also, $170k later, we're ReadMe.com instead of .io these days!)