RDoc is an application that produces documentation for one or more Ruby source
files. RDoc includes the +rdoc+ and +ri+ tools for generating and displaying
online documentation.

At this point in time, RDoc 2.x is a work in progress and may incur further
API changes beyond what has been made to RDoc 1.0.1. Command-line tools are
largely unaffected, but internal APIs may shift rapidly.

See RDoc for a description of RDoc's markup and basic use.