Renamed chapter 10 to 11

chapter11/App.test.js

@@ -0,0 +1,9 @@
+import React from 'react';
+import App from './App';
+
+import renderer from 'react-test-renderer';
+
+it('renders without crashing', () => {
+  const rendered = renderer.create(<App />).toJSON();
+  expect(rendered).toBeTruthy();
+});