Add warning to only use convex hull points when setting the point property for convex polygon shape

(cherry picked from commit 6b18614de7b4b5a67bbf6b357343bfdece7c3efb)

doc/classes/ConvexPolygonShape2D.xml

@@ -20,7 +20,7 @@
 	</methods>
 	<members>
 		<member name="points" type="PoolVector2Array" setter="set_points" getter="get_points" default="PoolVector2Array(  )">
-			The polygon's list of vertices. Can be in either clockwise or counterclockwise order.
+			The polygon's list of vertices. Can be in either clockwise or counterclockwise order. Only set this property with convex hull points, use [method set_point_cloud] to generate a convex hull shape from concave shape points.
 		</member>
 	</members>
 	<constants>