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

_examples/overview/main.go

@@ -83,7 +83,7 @@ func main() {
 	})
 
 	// Listen for incoming HTTP/1.x & HTTP/2 clients on localhost port 8080.
-	app.Run(iris.Addr(":8080"), iris.WithCharset("UTF-8"))
+	app.Listen(":8080", iris.WithCharset("UTF-8"))
 }
 
 func logThisMiddleware(ctx iris.Context) {