[css-values-4][editorial] Don't imply that <string> is only literals. #6506

Author: tabatkins

css-values-4/Overview.bs

@@ -754,9 +754,10 @@ Author-defined Identifiers: the <<custom-ident>> type</h3>
 <h3 id="strings">
 Quoted Strings: the <<string>> type</h3>
 
-	[=Strings=] are denoted by <dfn id="string-value">&lt;string></dfn>
-	and consist of a sequence of characters delimited by double quotes or
-	single quotes. They correspond to the <<string-token>> production
+	[=Strings=] are denoted by <dfn id="string-value">&lt;string></dfn>.
+	When written literally,
+	they consist of a sequence of characters delimited by double quotes or single quotes,
+	corresponding to the <<string-token>> production
 	in the <a href="https://www.w3.org/TR/css-syntax/">CSS Syntax Module</a> [[!CSS-SYNTAX-3]].
 
 	<div class=example>