[css-values-5] Drop var() vocabulary definition

Author: fantasai

css-values-5/Overview.bs

@@ -2750,7 +2750,7 @@ Appendix A: Arbitrary Substitution Functions</h2>
 	Note: See, for example, [=resolve a var() function=].
 
 	<div algorithm>
-		To <dfn export local-lt="substitute|substitution" lt="substitute a var()|var() substitution|substitute arbitrary substitution function|arbitrary substitution">substitute arbitrary substitution functions</dfn> in a |value|:
+		To <dfn export local-lt="substitute|substitution" lt="substitute arbitrary substitution function|arbitrary substitution">substitute arbitrary substitution functions</dfn> in a |value|:
 
 		1. [=list/For each=] [=arbitrary substitution function=] |func|
 			in |value|: