[docs] Fix doc.go (#333)

Addresses https://github.com/gorilla/mux/pull/294#discussion_r162309666

doc.go

@@ -239,8 +239,7 @@ as well:
 	                                 "category", "technology",
 	                                 "id", "42")
 
-Since **vX.Y.Z**, mux supports the addition of middlewares to a [Router](https://godoc.org/github.com/gorilla/mux#Router), which are executed if a
-match is found (including subrouters). Middlewares are defined using the de facto standard type:
+Mux supports the addition of middlewares to a Router, which are executed in the order they are added if a match is found, including its subrouters. Middlewares are (typically) small pieces of code which take one request, do something with it, and pass it down to another middleware or the final handler. Some common use cases for middleware are request logging, header manipulation, or ResponseWriter hijacking.
 
 	type MiddlewareFunc func(http.Handler) http.Handler