[css-values-5][editorial] Typo (#12435)

Author: cdoublev

css-values-5/Overview.bs

@@ -224,7 +224,7 @@ Commas in Function Arguments</h4>
 	* <<declaration-value>>
 
 	For legacy compat reasons,
-	the <<declaration-value>> defined the fallback value for ''var()''
+	the <<declaration-value>> defined for the fallback value of ''var()''
 	is a <dfn export>non-strict comma-containing production</dfn>.
 	It ignores the rules restricting what it can contain
 	when it does not start with a "{" token: