Added multiple elements examples to list.

examples/index.html

@@ -312,6 +312,7 @@
 				"webgl_multiple_canvases_circle",
 				"webgl_multiple_canvases_complex",
 				"webgl_multiple_canvases_grid",
+				"webgl_multiple_elements",
 				"webgl_multiple_views",
 				"webgl_nearestneighbour",
 				"webgl_octree",