[css-text-decor-3] Update Changes list.

Author: fantasai

css-text-decor-3/Overview.bs

@@ -1009,6 +1009,18 @@ Appendix B: Default UA Stylesheet</h2>
 <h2 class="no-num" id="changes">Appendix C:
 Changes</h2>
 
+<h3 class="no-num" id="changes-2018">
+Changes since the <a href="https://www.w3.org/TR/2019/CR-css-text-decor-3-20190813/">August 2019 Candidate Recommendation</a></h3>
+
+	Changes include:
+	<ul>
+		<li>Clarify that 'text-shadow' animates as a [=shadow list=] like 'box-shadow'.
+		(<a href="https://github.com/w3c/csswg-drafts/pull/4375">Issue 4375</a>)
+		<li>Be explicit about properties that apply to text.
+		(<a href="https://github.com/w3c/csswg-drafts/issues/5303">Issue 5303</a>)
+		<li>Minor editorial fixes.
+	</ul>
+
 <h3 class="no-num" id="changes-2018">
 Changes since the <a href="https://www.w3.org/TR/2018/CR-css-text-decor-3-20180703/">July 2018 Candidate Recommendation</a></h3>