fixed RTD link from fork to official docs

README.md

@@ -3,7 +3,7 @@ weed-fs
 
 [![Build Status](https://travis-ci.org/chrislusf/weed-fs.svg?branch=master)](https://travis-ci.org/chrislusf/weed-fs)
 [![GoDoc](https://godoc.org/github.com/chrislusf/weed-fs/go?status.svg)](https://godoc.org/github.com/chrislusf/weed-fs/go)
-[![RTD](https://readthedocs.org/projects/ernadoweed-fs/badge/?version=latest)](http://ernadoweed-fs.readthedocs.org/en/latest/)
+[![RTD](https://readthedocs.org/projects/weed-fs/badge/?version=latest)](http://weed-fs.readthedocs.org/en/latest/)
 
 An official mirror of code.google.com/p/weed-fs. 
 Moving to github.com to make cooperations easier.