Update contributing guide

Author: timomeh

CONTRIBUTING.md

@@ -2,20 +2,21 @@
 
 You can contribute by:
 
-* Reporting Bugs.
-* Answering Issues and helping people.
-* Making the Documentation better.
-* Fixing issues or adding new features through Pull Requests.
+- Reporting Bugs.
+- Answering Issues and helping people.
+- Making the Documentation better.
+- Fixing issues or adding new features through Pull Requests.
 
 ## Local setup
 
 1.  Fork and clone it
-2.  `npm install && npm link react-native-material-bottom-navigation`
-3.  `cd examples/Playground && npm install && npm link`
+2.  `npm install && npm link`
+3.  `cd examples/Playground && npm install && npm link react-native-material-bottom-navigation`
 
-## Run tests
+## Run tests & lint files
 
 1.  `npm test`
+2.  `npm run lint`
 
 ## Run the example app