Update free-programming-books.md

free-programming-books.md

@@ -908,6 +908,7 @@
 
 ### Go
 * [An Introduction to Programming in Go](http://www.golang-book.com/)
+* [Building Web Apps with Go](http://codegangsta.gitbooks.io/building-web-apps-with-go/content/)
 * [Build Web Application with Golang](https://docs.google.com/file/d/0B2GBHFyTK2N8TzM4dEtIWjBJdEk/)
 * [Go Bootcamp](http://www.golangbootcamp.com/book) - Matt Aimonetti
 * [Go by Example](https://gobyexample.com/)