[css-scroll-snap] Add issue about switching 1d vs 2d on the scroll-snap-type property instead.

Author: tabatkins

css-scroll-snap/Overview.bs

@@ -531,6 +531,10 @@ Scroll Snapping Alignment: the 'scroll-snap-align' property {#scroll-snap-alignm
 			the position applies to both axises.
 	</dl>
 
+	Issue: Or should 1d vs 2d be switched via 'scroll-snap-type'?
+	Then there's no grammar ambiguity.
+	Is there any use-case for doing both 1d and 2d in a single scroll container?
+
 	Since the purpose of scroll snapping is to align content within the viewport
 	for optimal viewing:
 	in all cases, the specified alignment creates a valid <a>snap position</a>