[css-images-4] Added Changes section

Author: LeaVerou

css-images-4/Overview.bs

@@ -1525,6 +1525,22 @@ Serialization {#serialization}
 Note: No change from [[css3-images]].
 
 Privacy and Security Considerations {#privsec}
-==============================================
 
 Note: No change from [[css3-images]].
+
+Changes {#changes}
+=================================================
+
+<h3 class="no-num">Changes Since the <a href="https://www.w3.org/TR/2012/WD-css4-images-20120911/">11 September 2012 Working Draft</a></h3>
+
+- Added <a href="#color-stop-syntax">color interpolation hints</a>
+- Added the <a href="#color-stop-syntax">two location syntax</a> for gradient color stops
+- Added start angles to <a href="#conic-gradients">conic gradients</a>
+- Text that is identical to [[css3-images]] has been replaced with a reference to [[css3-images]].
+
+<h3 class="no-num">Changes Since Level 3</h3>
+
+- Added the ''image()'' notation (deferred from Level 3)
+- Added the 'image-resolution' property (deferred from Level 3)
+- Added the ''element()'' notation (deferred from Level 3)
+- Added <a href="#conic-gradients">conic gradients</a>