To "how you build such a site in Clojure" the answer is that the entire Clojure ecosystem shies away from monolithic web frameworks and prepackaged solutions ala rails. Instead, Clojure libraries tend to pick a single feature or some small set of fetures, cover them well, expose a simple API and make composition trivial rather than trying to solve all possible problems.
Dash integration... Dash only makese sense for languages for which the documentation isn't trivially introspected such as Java. Clojure has the clojure.repl library (http://grimoire.arrdem.com/1.6.0/clojure.repl/) which is designed to solve this problem by exposing Clojure documentation to users in their interactive development (REPL) sessions. As I explain at some length in the Grimoire announcement post (http://arrdem.com/2014/07/12/of_mages_and_grimoires/) Grimoire seeks to fill a fumdimentally different niche than Dash. Clojure already has docs, and those docs are already handy for users aware of clojure.repl. Grimoire seeks to solve the problem of documenting the various ins and outs of the standard library which do _not_ appear in the official Clojure docs and which are currently spread out across any number of other low PageRank score community sites.