updates

step1-05/demo/src/App.tsx

@@ -1,15 +1,10 @@
 import React from 'react';
-import { TodoFooter } from './components/TodoFooter';
-import { TodoHeader } from './components/TodoHeader';
-import { TodoList } from './components/TodoList';
 
 export class TodoApp extends React.Component<any, any> {
   render() {
     return (
       <div>
-        <TodoHeader />
-        <TodoList />
-        <TodoFooter />
+        <p>Hello World</p>
       </div>
     );
   }