Update 2. 🌈 Building App.md

changed npm start to npm run dev

Add MetaMask connect button to your react app/Building & Shipping/2. 🌈 Building App.md

@@ -18,7 +18,7 @@ This will first create a helloreact folder and then my-app, a basic react applic
 
 ```bash
 cd my-app
-npm start
+npm run dev
 ```
 
 This will start your server and automatically open a window for you, where you can see the default react app. You will see something like the following image.
@@ -170,7 +170,7 @@ export default App;
 Go ahead and run the following command in the terminal.
 
 ```bash
-npm start
+npm run dev
 ```
 
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