docs(readme): fix appveyor badge

Author: curbengh

README.md

@@ -3,7 +3,7 @@
 [![Build Status](https://travis-ci.org/hexojs/hexo-fs.svg?branch=master)](https://travis-ci.org/hexojs/hexo-fs)
 [![NPM version](https://badge.fury.io/js/hexo-fs.svg)](https://www.npmjs.com/package/hexo-fs)
 [![Coverage Status](https://img.shields.io/coveralls/hexojs/hexo-fs.svg)](https://coveralls.io/r/hexojs/hexo-fs?branch=master)
-[![Build status](https://ci.appveyor.com/api/projects/status/tommy351/hexo-fs/branch/master?svg=true)](https://ci.appveyor.com/project/tommy351/hexo-fs/branch/master)
+[![Build status](https://ci.appveyor.com/api/projects/status/github/hexojs/hexo-fs?svg=true)](https://ci.appveyor.com/project/tommy351/hexo-fs/branch/master)
 [![dependencies Status](https://david-dm.org/hexojs/hexo-fs/status.svg)](https://david-dm.org/hexojs/hexo-fs)
 [![devDependencies Status](https://david-dm.org/hexojs/hexo-fs/dev-status.svg)](https://david-dm.org/hexojs/hexo-fs?type=dev)