[css-scroll-snap-1] Clarify that programmatic scrolls are also subject to scroll-snap. Fixs #2593.

Author: tabatkins

css-scroll-snap-1/Overview.bs

@@ -207,7 +207,8 @@ Overview {#overview}
     Using the 'scroll-snap-type' property on the relevant <a>scroll container</a>,
     the author can request a particular bias
     for the scrollport to land on a <a>snap position</a>
-    after scrolling operations.
+    after scrolling operations
+    (including programmatic scrolls such as the {{Window/scrollTo()}} method).
 
     <a>Snap positions</a> are specified
     as a particular alignment ('scroll-snap-align')