[css-images] Fix #458

Author: LeaVerou

css-images/Overview.bs

@@ -866,7 +866,7 @@ Gradient Color-Stops {#color-stop-syntax}
 -----------------------------------------
 
 	<pre class=prod>
-		<dfn>&lt;color-stop-list></dfn> = <<color-stop>>{2,}
+		<dfn>&lt;color-stop-list></dfn> = <<color-stop>>#{2,}
 		<dfn>&lt;color-stop></dfn> = <<color>> <<length-percentage>>?
 	</pre>