Edit readme - temporal solution #1

@@ -20,7 +20,20 @@ The main goal of this project is not to make something useful but to learn/use a
 
 1. Clone the repo
 $ git clone http://khuhub.khu.ac.kr/2019102244/weather_chatbot.git <your_dir>
-$ cd <your_dir>/server && npm start
+
+2. Install node_modules
+* install at server dir
+$ cd <your_dir>/server
+$ npm install
+
+* install at client dir
+$ cd ..
+$ cd client
+$ npm install
+
+3. start the web-app
+$ cd ..
+$ cd server && npm start
 
 2. Load the repo on web browser
 localhost:8080