react-express-mysql: use create-react-app template

Signed-off-by: Jérémie Drouet <jeremie.drouet@gmail.com>

react-express-mysql/backend/index.js

@@ -24,7 +24,7 @@ var app = express();
 app.use(morgan('common'));
 
 app.get('/', function (req, res) {
-  res.send('Hello Docker World\n');
+  res.json({ message: 'Hello Docker World!' });
 });
 
 app.get('/healthz', function (req, res) {