Added "A tour of Go" Resource online

Author: Zhang Dan Jie

README.md

@@ -178,6 +178,7 @@ Free to [read online](https://thewhitetulip.gitbooks.io/webapp-with-golang-anti-
 Resources
 ====
 
+###[A tour of Go](https://tour.golang.org/)
 ###[Video: Learn Go Syntax in one video](http://www.youtube.com/watch?v=CF9S4QZuV30)
 ###[Tutorials: Go by Example](https://gobyexample.com/)
 ###[Go Fundamentals Video Training](http://shop.oreilly.com/category/learning-path/go-fundamentals.do)