Kotlin tutorials resource added (#4522)

* Added data structure course by mycodeschool

* link changed to playlist

* Added kotlin tutorial resource

This resource is provided by Tutorialspoints.

* arranged in a order

* kotlin tutorial docs added(official)

free-programming-interactive-tutorials-en.md

@@ -18,6 +18,7 @@
 * [Java](#java)
 * [JavaScript](#javascript)
   * [Angular.js](#angularjs)
+* [Kotlin](#kotlin)
 * [Language Agnostic](#language-agnostic)
   * [Operating Systems](#operating-systems)
 * [Lisp](#lisp)
@@ -161,6 +162,11 @@
 * [Learn AngularJS with free interactive lessons](http://www.learn-angular.org)
 
 
+### Kotlin
+
+* [Kotlin tutorial](https://kotlinlang.org/docs/tutorials/)
+
+
 ### Language Agnostic
 
 * [CodeCombat](http://codecombat.com) - Python, JavaScript, CoffeeScript, Clojure, Lua, Io