examples: replace all app.Run(iris.Addr(...)) with app.Listen just for the shake of simplicity, both are doing the same exact thing as it's described on the http listening first example.

Former-commit-id: d20afb2e899aee658a8e0ed1693357798df93462

cache/cache.go

@@ -17,7 +17,7 @@ Example code:
 		 	app := iris.Default()
 		 	middleware := cache.Handler(2 *time.Minute)
 		 	app.Get("/hello", middleware, h)
-		 	app.Run(iris.Addr(":8080"))
+		 	app.Listen(":8080")
 		 }
 
 		 func h(ctx iris.Context) {