remove handler from app (#129)

diff --git a/pkgs/shelf_router/README.md b/pkgs/shelf_router/README.md
index 6738d15..15cf02b 100644
--- a/pkgs/shelf_router/README.md
+++ b/pkgs/shelf_router/README.md
@@ -27,7 +27,7 @@
   return Response.ok('hello $user');
 });
 
-var server = await io.serve(app.handler, 'localhost', 8080);
+var server = await io.serve(app, 'localhost', 8080);
 ```
 
 See reference documentation of `Router` class for more information.