[css-syntax-3] Clarify that all the non-ASCII ranges are inclusive, like the other ranges in the spec. w3c#8861

Author: tabatkins

css-syntax-3/Overview.bs

@@ -848,6 +848,8 @@ Definitions</h3>
 			* between U+FDF0 and U+FFFD
 			* greater than or equal to U+10000
 
+			All of these ranges are inclusive.
+
 			<details class=note>
 				<summary>Why these character, specifically?</summary>