docs: update readme with yarn commands (carbon-design-system#3486)

README.md

@@ -10,20 +10,20 @@ This project was bootstrapped with [Create React App](https://github.com/faceboo
 
 In the project directory, you can run:
 
-### `npm start`
+### `yarn start`
 
 Runs the app in the development mode.<br>
 Open [http://localhost:3000](http://localhost:3000) to view it in the browser.
 
 The page will reload if you make edits.<br>
 You will also see any lint errors in the console.
 
-### `npm test`
+### `yarn test`
 
 Launches the test runner in the interactive watch mode.<br>
 See the section about [running tests](https://facebook.github.io/create-react-app/docs/running-tests) for more information.
 
-### `npm run build`
+### `yarn build`
 
 Builds the app for production to the `build` folder.<br>
 It correctly bundles React in production mode and optimizes the build for the best performance.
@@ -33,7 +33,7 @@ Your app is ready to be deployed!
 
 See the section about [deployment](https://facebook.github.io/create-react-app/docs/deployment) for more information.
 
-### `npm run eject`
+### `yarn eject`
 
 **Note: this is a one-way operation. Once you `eject`, you can’t go back!**
 
@@ -69,6 +69,6 @@ This section has moved here: https://facebook.github.io/create-react-app/docs/ad
 
 This section has moved here: https://facebook.github.io/create-react-app/docs/deployment
 
-### `npm run build` fails to minify
+### `yarn build` fails to minify
 
 This section has moved here: https://facebook.github.io/create-react-app/docs/troubleshooting#npm-run-build-fails-to-minify