Added jsdocs

src/physics/arcade/World.js

@@ -1735,7 +1735,22 @@ var World = new Class({
     },
 
     /**
-     * Tests if Game Objects overlap and separates them (if possible).
+     * Performs a collision check and separation between the two physics enabled objects given, which can be single
+     * Game Objects, arrays of Game Objects, Physics Groups, arrays of Physics Groups or normal Groups.
+     *
+     * If you don't require separation then use {@link #overlap} instead.
+     * 
+     * If two Groups or arrays are passed, each member of one will be tested against each member of the other.
+     *
+     * If one Group **only** is passed (as `object1`), each member of the Group will be collided against the other members.
+     *
+     * Two callbacks can be provided. The `collideCallback` is invoked if a collision occurs and the two colliding
+     * objects are passed to it.
+     *
+     * Arcade Physics uses the Projection Method of collision resolution and separation. While it's fast and suitable
+     * for 'arcade' style games it lacks stability when multiple objects are in close proximity or resting upon each other.
+     * The separation that stops two objects penetrating may create a new penetration against a different object. If you
+     * require a high level of stability please consider using an alternative physics system, such as Matter.js.
      *
      * @method Phaser.Physics.Arcade.World#collide
      * @since 3.0.0