added docs to constructor

canvas2D/src/Engine/babylon.group2d.ts

@@ -43,6 +43,8 @@
          * - rotation: the initial rotation (in radian) of the primitive. default is 0
          * - scale: the initial scale of the primitive. default is 1. You can alternatively use scaleX &| scaleY to apply non uniform scale
          * - dontInheritParentScale: if set the parent's scale won't be taken into consideration to compute the actualScale property
+         * - trackNode: if you want the ScreenSpaceCanvas to track the position of a given Scene Node, use this setting to specify the Node to track
+         * - trackNodeOffset: if you use trackNode you may want to specify a 3D Offset to apply to shift the Canvas
          * - opacity: set the overall opacity of the primitive, 1 to be opaque (default), less than 1 to be transparent.
          * - zOrder: override the zOrder with the specified value
          * - origin: define the normalized origin point location, default [0.5;0.5]