[css-snappoints] Adding advisement to authors warning about dangers of mandatory snapping

Author: ChumpChief

css-snappoints/Overview.bs

@@ -293,6 +293,15 @@ Scroll Snap Types: the 'scroll-snap-type' property {#scroll-snap-type}
             If the content changes such that the scroll container would no longer be <a>snapped</a> (e.g. content is added, moved, deleted, resized) to the same snap position it was snapped to before the content change and that same snap position still exists (e.g. its associated element was not deleted) and is reachable, the scroll container must be re-snapped to that same snap position after the content change.
     </dl>
 
+    Advisement:
+    Authors should use mandatory snap positions with consideration of
+    varyingly-sized screens and (if applicable) varying-sized content.
+    In particular, although access to snapped elements larger than the viewport
+    is <a href="#snap-overflow">handled by the UA</a>,
+    if authors assign mandatory snapping to non-adjacent siblings,
+    content in between can become inaccessible
+    in cases where it is longer than the screen.
+
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