[css-transitions-2] Update changes section to be current.

Author: dbaron

css-transitions-2/Overview.bs

@@ -644,7 +644,9 @@ No new security considerations have been reported on this specification.
 
 <h3 id="changes-20230905">Changes since First Public Working Draft (5 September 2023)</h3>
 
-<p>None yet</p>
+<ul>
+  <li>Define the order of {{transitioncancel}} events.</li>
+</ul>
 
 <h3 id="changes-fpwd">Changes since Level 1, in First Public Working Draft</h3>