Update Group.html

Change the example code to refer to the correct cube (B).

docs/api/objects/Group.html

@@ -28,7 +28,7 @@
 		cubeA.position.set( 100, 100, 0 );
 
 		var cubeB = new THREE.Mesh( geometry, material );
-		cubeA.position.set( -100, -100, 0 );
+		cubeB.position.set( -100, -100, 0 );
 
 		//create a group and add the two cubes
 		//These cubes can now be rotated / scaled etc as a group