Add npm install node-jsx

exercises/hello_react/problem.en.md

@@ -9,6 +9,8 @@ Run the three commands below.
 
 `$ npm install express-react-views`
 
+`$ npm install node-jsx`
+
 Next, create `program.js` and copy the code below into the file.
 
 ```

exercises/hello_react/problem.ko.md

@@ -9,6 +9,8 @@
 
 `$ npm install express-react-views`
 
+`$ npm install node-jsx`
+
 그런 다음, `program.js`를 만들어 다음과 같은 내용을 적습니다.
 
 ```

exercises/hello_react/problem.md

@@ -9,6 +9,8 @@
 
 `$ npm install express-react-views`
 
+`$ npm install node-jsx`
+
 次に `program.js` を作成し、以下のように記述してください。
 
 ```