[css-scrollbars] Post publication update

* Link to latest WD
* Open new subsection in the changes section

Author: frivoal

css-scrollbars-1/Overview.bs

@@ -7,6 +7,7 @@ Status: ED
 Work Status: Revising
 ED: https://drafts.csswg.org/css-scrollbars/
 TR: https://www.w3.org/TR/css-scrollbars-1/
+Previous version: https://www.w3.org/TR/2021/WD-css-scrollbars-1-20210805/
 Previous version: https://www.w3.org/TR/2018/WD-css-scrollbars-1-20180925/
 Repository: https://github.com/w3c/csswg-drafts/tree/master/css-scrollbars-1 css-scrollbars
 Editor: Tantek Çelik, Mozilla https://www.mozilla.org/, http://tantek.com/contact, w3cid 1464
@@ -253,8 +254,14 @@ from
 
 This appendix is <em>informative</em>.
 
-This appendix describes changes from the
-<a href="https://www.w3.org/TR/2018/WD-css-scrollbars-1-20180925/">First Public Working Draft (FPWD) of 25 Sep 2018</a>.
+<h3 class="no-num" id=changes-since-2021-08-05">
+Changes from the <a href="https://www.w3.org/TR/2021/WD-css-scrollbars-1-20210805/">2021-08-05 Working Draft</a></h3>
+
+None yet.
+
+<h3 class="no-num" id=changes-since-2018-09-25">
+Changes from the <a href="https://www.w3.org/TR/2018/WD-css-scrollbars-1-20180925/">2018-09-25 First Public Working Draft</a></h3>
+
 <ul>
 <li><a href="https://github.com/w3c/csswg-drafts/issues/6438">#6538</a>:
     removed <css>light</css> and <css>dark</css> values of 'scrollbar-color'
@@ -268,7 +275,6 @@ This appendix describes changes from the
 </li>
 <li><a href="https://github.com/w3c/csswg-drafts/issues/3315">#3315</a>: 
     More and updated accessibility considerations for scrollbar-color and scrollbar-width.
-</li>
 </ul>
 
 <h2 class="no-num" id="security-privacy-considerations">Appendix C. Considerations for Security and Privacy</h2>