Added in interactive programming resources for Go, Kotlin, and added in an R section (#5786)

* Update free-programming-interactive-tutorials-en.md

* Update free-programming-interactive-tutorials-en.md

* Update free-programming-interactive-tutorials-en.md

* Update free-programming-interactive-tutorials-en.md

* Update free-programming-interactive-tutorials-en.md

more/free-programming-interactive-tutorials-en.md

@@ -36,6 +36,7 @@
 * [PHP](#php)
 * [PostgreSQL](#postgresql)
 * [Python](#python)
+* [R](#r)
 * [Ruby](#ruby)
 * [Rust](#rust)
 * [Scala](#scala)
@@ -140,6 +141,7 @@
 
 * [Go Koans](https://github.com/cdarwin/go-koans)
 * [Go Tutorial](https://www.w3schools.com/go/) - W3Schools
+* [Learn Go](https://www.codecademy.com/learn/learn-go) - Google, Robert Griesemer, Rob Pike, and Ken Thompson (Codecademy) *(account required)*
 * [Start using Go](https://docs.microsoft.com/en-us/learn/paths/go-first-steps/) - Microsoft
 * [The Go Tutorial](http://tour.golang.org)
 
@@ -223,6 +225,7 @@
 ### Kotlin
 
 * [Kotlin tutorial](https://kotlinlang.org/docs/tutorials/)
+* [Learn Kotlin](https://www.codecademy.com/learn/learn-kotlin) - Galina Podstrechnaya, Alex DiStasi (Codecademy) *(account required)*
 
 
 ### Language Agnostic
@@ -303,6 +306,12 @@
 * [Python Tutorial](https://www.w3schools.com/python) - W3Schools
 
 
+## R
+
+* [Learn R](https://www.codecademy.com/learn/learn-r) - Codecademy *(account required)*
+* [R Tutorial](https://www.w3schools.com/r) - W3Schools
+
+
 ### Ruby
 
 * [CodeCademy Ruby](https://www.codecademy.com/learn/ruby)