Update free-programming-playgrounds.md (#8188)

* Update free-programming-playgrounds.md

* added multiple language category

* fix linting warning

* fix liniting warning

more/free-programming-playgrounds.md

@@ -23,6 +23,7 @@
     * [AngularJS](#angularjs)
 * [Kotlin](#kotlin)
 * [Kubernetes](#kubernetes)
+* [Multiple Languages](#multiple-languages)
 * [.Net](#dotnet)
 * [Nim](#nim)
 * [Node.js](#nodejs)
@@ -206,6 +207,11 @@
 * [Play with Kubernetes](https://labs.play-with-k8s.com)
 
 
+### Multiple Languages
+
+* [CodeChef](https://www.codechef.com/ide)
+
+
 ### <a id="dotnet"></a>.NET
 
 * [.NET Fiddle](https://dotnetfiddle.net)