Merge pull request #3333 from ewilligers/calc-serialization-example

[css-values] Serialize % before px in calc example

Author: tabatkins

css-values-4/Overview.bs

@@ -2442,7 +2442,7 @@ Serialization</h4>
 		For example, ''calc(20px + 30px)'' would serialize as ''calc(50px)'' as a specified value,
 		or as ''50px'' as a computed value.
 
-		A value like ''calc(20px + 0%)'' would serialize as ''calc(20px + 0%)'',
+		A value like ''calc(20px + 0%)'' would serialize as ''calc(0% + 20px)'',
 		maintaining both terms in the serialized value.
 		(It's important to maintain zero-valued terms,
 		so the ''calc()'' doesn't suddenly "change shape" in the middle of a transition