Update README.md

Author: cktang88

README.md

@@ -1,7 +1,7 @@
 # Vaken
 
 [![CircleCI](https://img.shields.io/circleci/build/github/VandyHacks/vaken.svg)](https://circleci.com/gh/VandyHacks/vaken)
-[![codecov](https://codecov.io/gh/VandyHacks/vaken/branch/dev/graph/badge.svg)](https://codecov.io/gh/VandyHacks/vaken)
+[![codecov](https://codecov.io/gh/VandyHacks/vaken/branch/staging/graph/badge.svg)](https://codecov.io/gh/VandyHacks/vaken)
 ![GitHub](https://img.shields.io/github/license/vandyhacks/vaken.svg)
 [![Depfu](https://badges.depfu.com/badges/cef18db6a35fb2d23a3a917ea9b6d852/overview.svg)](https://depfu.com/github/VandyHacks/vaken?project_id=7955)
 [![Maintainability](https://api.codeclimate.com/v1/badges/945dac4210d3058caa78/maintainability)](https://codeclimate.com/github/VandyHacks/vaken/maintainability)