use `actix_rt::block_on` in examples

actix-web/examples/macroless.rs

@@ -8,7 +8,7 @@ async fn index(req: HttpRequest) -> &'static str {
 fn main() -> std::io::Result<()> {
     env_logger::init_from_env(env_logger::Env::new().default_filter_or("info"));
 
-    rt::System::new().block_on(
+    rt::block_on(
         HttpServer::new(|| {
             App::new()
                 .wrap(middleware::Logger::default())

actix-web/src/rt.rs

@@ -13,7 +13,7 @@
 //! }
 //!
 //! # fn main() -> std::io::Result<()> {
-//! rt::System::new().block_on(
+//! rt::block_on(
 //!     HttpServer::new(|| {
 //!         App::new()
 //!             .wrap(middleware::Logger::default())