Readme should show basic example with empty path

[martinklepsch]

Currently most of the examples in the README expect something after the /. Given that matching the "empty path" is a very common scenario users will want to accomplish it could be documented more prominently. I don't have more than anecdotal data on this but I'd expect that it is also often a source of confusion.

(def my-routes ["/" {"" :index ; I'm not even sure if this is correct ;D
                     "article.html" :article}])

[SevereOverfl0w]

fwiw, it's correct.