Adding grasshopper for playgrounds for javascript (#6220)

* Adding grasshopper for playgrounds for javascript

Added grasshopper as a programming playground

* Update more/free-programming-playgrounds.md
Co-authored-by: NDavid Ordás <3125580+davorpa@users.noreply.github.com>
Co-authored-by: NDavid Ordás <3125580+davorpa@users.noreply.github.com>

more/free-programming-playgrounds.md

@@ -142,6 +142,7 @@
 * [CodePen](https://codepen.io)
 * [CodeSandbox.io](https://codesandbox.io)
 * [Esfiddle](https://esfiddle.net)
+* [Grasshopper](https://grasshopper.app) *(Google account required)*
 * [JSBin](http://jsbin.com)
 * [JSFiddle](http://jsfiddle.net)
 * [Plunker](http://plnkr.co)