Reorganize method routers for handlers and services (#405)

* Re-organize method routing for handlers

* Re-organize method routing for services

* changelog

examples/graceful_shutdown/src/main.rs

@@ -5,7 +5,7 @@
 //! kill or ctrl-c
 //! ```
 
-use axum::{handler::get, response::Html, Router};
+use axum::{response::Html, routing::get, Router};
 use std::net::SocketAddr;
 
 #[tokio::main]