Update changes list

Author: fantasai

css-values-4/Overview.bs

@@ -4,9 +4,10 @@ Group: CSSWG
 Shortname: css-values
 Level: 4
 Status: ED
-Work Status: Testing
+Work Status: Exploring
 ED: https://drafts.csswg.org/css-values/
 TR: https://www.w3.org/TR/css-values/
+Previous version: https://www.w3.org/TR/2018/WD-css-values-4-20180814/
 Editor: Tab Atkins, Google, http://xanthir.com/contact/, w3cid 42199
 Editor: fantasai, http://fantasai.inkedblade.net/contact, w3cid 35400
 Abstract: This CSS module describes the common values and units that CSS properties accept and the syntax used for describing them in CSS property definitions.
@@ -2962,6 +2963,12 @@ Acknowledgments</h2>
 <h2 class="no-num" id="changes">
 Changes</h2>
 
+	Changes since the <a href="https://www.w3.org/TR/2018/WD-css-values-4-20180814/">14 August 2018 Working Draft</a>:
+
+	<ul>
+		<li>Added rules for interpolation per value type, and clarified computed values.
+	</ul>
+
 	Changes since <a href="http://www.w3.org/TR/css-values-3/">Level 3</a>:
 
 	<ul>