[css-lists-3] Comment out ol[reversed] handling; clarify that style sheet is illustrative; add issue noting ongoing discussions about ol[reversed].

Author: fantasai

css-lists-3/Overview.bs

@@ -1386,7 +1386,12 @@ Appendix A: Sample Style Sheet For HTML</h2>
 
 	<em>This section is informative, not normative.
 	The [[HTML]] <a href="https://html.spec.whatwg.org/multipage/rendering.html#lists">Rendering</a> chapter
-	defines the normative default properties that apply to HTML lists.</em>
+	defines the normative default properties that apply to HTML lists;
+	this sample style sheet is provided to illustrate the CSS features
+	using familiar markup conventions.</em>
+
+	ISSUE: Discussion of how to support <code>ol[reversed]</code> list numbering in CSS is ongoing.
+	See, e.g. <a href="https://github.com/w3c/csswg-drafts/issues/4181">Issue 4181</a>.
 
 	<pre>
 		/* Set up list items */
@@ -1423,6 +1428,7 @@ Appendix A: Sample Style Sheet For HTML</h2>
 			counter-set: list-item attr(value integer, 1);
 		}
 
+<!--
 		/* Handling reversed lists */
 		ol[reversed] {
 			counter-reset: list-item calc(attr(start integer, **magic**) + 1);
@@ -1431,6 +1437,7 @@ Appendix A: Sample Style Sheet For HTML</h2>
 		ol[reversed] > li {
 			/* HTML implies 'counter-increment: list-item -1' */
 		}
+-->
 
 		/* Box Model Rules */
 		ol, ul {