use npm instead of yarn

Author: ibarrajo

README.md

@@ -8,31 +8,24 @@
 
 
 
-### Prerequesites
-
-```
-# install yarn
-$ npm install --global yarn
-```
-
 ### Installation
 
 ```
-$ yarn
+$ npm install
 ```
 
 ### Local Development
 
 ```
-$ yarn start
+$ npm run start
 ```
 
 This command starts a local development server and opens up a browser window at http://localhost:3000/. Most changes are reflected live without having to restart the server.
 
 ### Build
 
 ```
-$ yarn build
+$ npm run build
 ```
 
 This command generates static content into the `build` directory and can be served using any static contents hosting service.
@@ -42,13 +35,13 @@ This command generates static content into the `build` directory and can be serv
 Using SSH:
 
 ```
-$ USE_SSH=true yarn deploy
+$ USE_SSH=true npm run deploy
 ```
 
 Not using SSH:
 
 ```
-$ GIT_USER=<Your GitHub username> yarn deploy
+$ GIT_USER=<Your GitHub username> npm run deploy
 ```
 
 If you are using GitHub pages for hosting, this command is a convenient way to build the website and push to the `gh-pages` branch.