Reorganize method routers for handlers and services (#405)

* Re-organize method routing for handlers

* Re-organize method routing for services

* changelog

examples/low-level-rustls/src/main.rs

@@ -4,7 +4,7 @@
 //! cargo run -p example-low-level-rustls
 //! ```
 
-use axum::{handler::get, Router};
+use axum::{routing::get, Router};
 use hyper::server::conn::Http;
 use std::{fs::File, io::BufReader, sync::Arc};
 use tokio::net::TcpListener;