Merge pull request #170 from zeta-o/develop

Update README.md

Author: Gery Hirschfeld

README.md

@@ -92,7 +92,7 @@ Install [Node.js and NPM](https://nodejs.org/en/download/)
 Install yarn globally
 
 ```bash
-yarn install yarn -g
+yarn global add yarn
 ```
 
 Install a MySQL database.