page decision-graph.html: get parameter from request by :word instead of "word"

[wangchunyang]

On the page http://clojure-liberator.github.io/liberator/tutorial/decision-graph.html, it mentions to use "word" to get value of request parameter:

(= "tiger" (get-in ctx [:request :params "word"])))

However it doesn't work on my running environment (ring 1.3.2). The value is nil. So I have to use this to get value of request parameter.

(= "tiger" (get-in ctx [:request :params :word])))

Is this a bug in page? Or, is there anything wrong in my running environment?
Thanks.