Add physics playground (#279)

* init author's work

* image updates

* text updates

* Physics playground language edit

Co-authored-by: Tatenda <[email protected]>
Co-authored-by: worktheclock <[email protected]>

Author: 3 people

sidebar.json

@@ -440,6 +440,10 @@
         "name": "Flappy Bird with Kaboom.js",
         "slug": "35-build-flappy-bird-with-kaboom"
       },
+      {
+        "name": "Physics playground with Kaboom.js",
+        "slug": "36-physics-playground-with-kaboom"
+      },
       {
         "name": "Pinboard project part 1: HTML & CSS",
         "slug": "pinboard-project-part-1"