Log Message:
Add ruby-redcarpet package version 3.0.0.

Redcarpet is Ruby library for Markdown processing that smells like
butterflies and popcorn.

Redcarpet used to be a drop-in replacement for Redcloth. This is no longer the
case since version 2 -- it now has its own API, but retains the old name. Yes,
that does mean that Redcarpet 2 is not backwards-compatible with the 1.X
versions.

Redcarpet is based on the [Sundown](https://www.github.com/vmg/sundown)
library. You might want to find out more about Sundown to see what makes this
Ruby library so awesome.