[css-fonts-4] Update changes

Author: svgeesus

css-fonts-4/Overview.bs

@@ -7396,6 +7396,11 @@ Changes
 <h3 id="changes-2021-07-29">Changes from the <a href="https://www.w3.org/TR/2021/WD-css-fonts-4-20210729/">29 July 2021 Working Draft</a> </h3>
 
 <ul>
+	<!--  to 17 Dec 2021 -->
+	<li>Clarified that functions and relative lengths in palettes are evaluated
+		within the root element's context</li>
+	<li>Added new section, overall changes since CSS Fonts 3</li>
+	<li>Added more font-palette-values examples</li>
 	<li>Renamed technology to tech</li>
 	<!-- to 03 Dec 2021 -->
 	<li>New 'math' value added to 'font-size'</li>