some ideas to improve the Journey Readme

Some notes in the Readme on what Journey does, and why it is different from the old Router would be great. In this PR are some ideas, and it would be great to start some discussion on what should be in the Readme.

So far, I only found 2 resources which might relate to what Journey does, and how it works:

* http://blog.bigbinary.com/2013/01/29/journey-into-rails-routing.html
* http://happstack.com/page/view-page-slug/16/comparison-of-4-approaches-to-implementing-url-routing-combinators-including-the-free-and-operational-monads