[css-grid-1][css-grid-2] Clarify animation type of grid-auto-* w3c#9440

Author: tabatkins

css-grid-1/Overview.bs

@@ -2367,7 +2367,7 @@ Implicit Track Sizing: the 'grid-auto-rows' and 'grid-auto-columns' properties</
 	Inherited: no
 	Percentages: see [[#track-sizing|Track Sizing]]
 	Computed value: see [[#track-sizing|Track Sizing]]
-	Animation type: by computed value type
+	Animation type: if the list lengths match, by computed value type per item; discrete otherwise
 	</pre>
 
 	The 'grid-auto-columns' and 'grid-auto-rows' properties specify

css-grid-2/Overview.bs

@@ -2528,7 +2528,7 @@ Implicit Track Sizing: the 'grid-auto-rows' and 'grid-auto-columns' properties</
 	Inherited: no
 	Percentages: see [[#track-sizing|Track Sizing]]
 	Computed value: see [[#track-sizing|Track Sizing]]
-	Animation type: by computed value type
+	Animation type: if the list lengths match, by computed value type per item; discrete otherwise
 	</pre>
 
 	The 'grid-auto-columns' and 'grid-auto-rows' properties specify