add ELB target health check code

@@ -30,9 +30,10 @@ const client = new line.Client(config);
 // about Express itself: https://expressjs.com/
 
 // test
-app.get('/get', (req, res)=> {
-	res.send('hello');
-})
+app.get('/', (req, res) => {
+	console.log('hello');
+	res.status(200);
+});
 
 // register a webhook handler with middleware
 // about the middleware, please refer to doc
@@ -113,6 +114,7 @@ function handleEvent(event) {
     });
   }
 
+
 app.listen(3000, function () {
   console.log('Linebot listening on port 3000!');
 });