documentation for using wrap-reload

https://github.com/ring-clojure/ring/blob/master/ring-devel/src/ring/middleware/reload.clj

It appears wrap-reload needs to be passed a handler as normal, but with the caveat that its referenced through a var (see https://github.com/mmcgrana/ring/issues/72).

Something along the lines of:

(def app
  (-> (compojure.core/routes my-routes)
      (compojure.handler/api)))

(def app-with-reload
  (ring.middleware.reload/wrap-reload #'app))

(defn -main []
  (ring.adapter.jetty/run-jetty #'app-with-reload {:port 8081 :join? false})
  (ring.adapter.jetty/run-jetty #'app-with-reload {:port 8082 :join? false}))

If instead wrap-reload is treated as a normal middleware—placed in the chain for app—it seems to work but the updated behavior is actually delayed by one request.

Raising this issue to hopefully get some documentation in wrap-reload that makes note that it needs the var reference; also it may be helpful for it to throw an exception if it's not passed a var to prevent accidental use as typical middleware.

Start with ring-devel/src/ring/middleware/reload.clj and the wrap-reload entry point. Document that the handler is passed through a var reference, include the example usage from the issue, and explain the delayed behavior when it is used as ordinary middleware; clarify whether the proposed invalid-argument exception is part of the documentation scope.