[css-counter-styles-3] Add the width descriptor to the API section.

Author: tabatkins

css-counter-styles-3/Overview.html

@@ -3419,6 +3419,8 @@ <h3 id=the-csscounterstylerule-interface><span class=secno>7.2. </span> The
 <!--
 	-->  readonly attribute DOMString range;
 <!--
+	-->  readonly attribute DOMString width;
+<!-- 
 	-->  readonly attribute DOMString fallback;
 <!--
 	-->}</pre>

css-counter-styles-3/Overview.src.html

@@ -2446,6 +2446,7 @@ <h3 id="the-csscounterstylerule-interface">
 	-->  readonly attribute DOMString prefix;&#xa;<!--
 	-->  readonly attribute DOMString suffix;&#xa;<!--
 	-->  readonly attribute DOMString range;&#xa;<!--
+	-->  readonly attribute DOMString width;&#xa;<!-- 
 	-->  readonly attribute DOMString fallback;&#xa;<!--
 	-->}</pre>