Add more docs to rectangle

git-svn-id: http://svn.openlayers.org/trunk/openlayers@6446 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Geometry/Rectangle.js

@@ -8,9 +8,12 @@
 
 /**
  * Class: OpenLayers.Geometry.Rectangle
- * A Rectangle is a simple geometry. It is specified by a point (x and y) 
- *     and dimensions (width and height), all of which are directly accessible 
- *     as properties.
+ * This class is *not supported*, and probably isn't what you're looking for.
+ *     Instead, most users probably want something like:
+ *     (code)
+ *     var poly = new OpenLayers.Bounds(0,0,10,10).toGeometry();
+ *     (end)
+ *     This will create a rectangular Polygon geometry. 
  * 
  * Inherits:
  *  - <OpenLayers.Geometry>