Add new Go courses (#5649)

* Add Go resources

* Revert "Add Go resources"

This reverts commit 6b7fd5c504.

* Added Go resources

* edit urls

* edit urls

* Update free-courses-en.md

courses/free-courses-en.md

@@ -332,6 +332,7 @@
 * [A Tour Of Go](https://tour.golang.org/welcome/1)
 * [Go Tutorial](http://www.tutorialspoint.com/go/index.htm)
 * [Golang \| Gin HTTP Framework](https://www.youtube.com/playlist?list=PL3eAkoh7fypr8zrkiygiY1e9osoqjoV9w) - Pragmatic Reviews
+* [Gophercises: Free Coding Exercises for Budding Gophers](https://gophercises.com) - Jon Calhoun (email address *required*)
 * [Learn Go Programming - Golang Tutorial for Beginners](https://www.youtube.com/watch?v=YS4e4q9oBaU) - FreeCodeCamp