Some time ago I read the changelog of a Ruby on Rails version (I think 3.1.0). In that was written that the documentation "system"/"software" was changed. The current can be browsed here.
What is the new documentation software used by Rails? Where I can find that and the related documentation? How should I use that?
screenshot http://pix.am/AeJE.png
This gives us a hint that it is made with RDoc. I thought, however, that they are using YARD now.