Change the badge to master

Author: alexcanessa

README.md

@@ -4,7 +4,7 @@
 [![npm version](https://badge.fury.io/js/github-release-notes.svg)](https://badge.fury.io/js/github-release-notes)
 [![Build Status](https://travis-ci.org/github-tools/github-release-notes.svg?branch=master)](https://travis-ci.org/github-tools/github-release-notes)
 [![Join the chat at https://gitter.im/github-release-notes/Lobby](https://badges.gitter.im/github-release-notes/Lobby.svg)](https://gitter.im/github-release-notes/Lobby?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
-[![Codecov](https://codecov.io/gh/github-tools/github-release-notes/branch/second-refactor/graph/badge.svg)](https://codecov.io/gh/github-tools/github-release-notes/)
+[![Codecov](https://codecov.io/gh/github-tools/github-release-notes/branch/master/graph/badge.svg)](https://codecov.io/gh/github-tools/github-release-notes/)
 [![npm downloads](https://img.shields.io/npm/dy/github-release-notes.svg)](https://www.npmjs.com/package/github-release-notes)
 
 ## Motivation