[css-scroll-snap-2] adding note about :snapped resolution timing

Author: argyleink

css-scroll-snap-2/Overview.bs

@@ -216,6 +216,9 @@ More specific options are defined as follows:
 			Matches the child snapped on the [=block=] axis.
 	</dl>
 
+Note: <a href="https://github.com/w3c/csswg-drafts/issues/6985#issuecomment-1049036401">Issue #6985</a><br>
+Need to figure out resolution of the initial frame.
+
 Snap Events {#todo}
 ===================