Update 'Update the Rendering' step number

Author: vmpstr

css-contain-2/Overview.bs

@@ -1636,7 +1636,7 @@ Restrictions and Clarifications {#cv-notes}
 		Determining the viewport intersection of the element
 		can be done with an internal version of an IntersectionObserver.
 		However, since the observations from this are dispatched at
-		step 13 of Update the Rendering,
+		step 14 of Update the Rendering,
 		any changes to the [=skipped contents|skipped=] (and thus painted) state
 		will not be visible to the user until the next frame's processing.
 		For this reason, updating the [=skipped contents|skipped=] state,