[css-values-3] Export dfn

Author: fantasai

css-values-3/Overview.bs

@@ -707,7 +707,7 @@ Range Restrictions and Range Definition Notation</h3>
 	then unless otherwise specified,
 	the declaration is invalid and must be <a href="https://www.w3.org/TR/CSS21/conform.html#ignore">ignored</a>.
 	Range restrictions can be annotated in the numeric type notation
-	using <dfn local-lt="bracketed range notation">CSS bracketed range notation</dfn>--
+	using <dfn export local-lt="bracketed range notation">CSS bracketed range notation</dfn>--
 	<code>[<var>min</var>,<var>max</var>]</code>--
 	within the angle brackets, after the identifying keyword,
 	indicating a closed range