[css-images-4] Update changes list

Author: fantasai

css-images-4/Overview.bs

@@ -2552,10 +2552,12 @@ Changes Since the <a href="https://www.w3.org/TR/2017/WD-css-images-4-20170413/"
 		* Align “Computed Value” and “Animation Type” lines across modules, tighten wording, and correct errors.
 		* Use the new [=CSS bracketed range notation=] where appropriate.
 		* Drop “Media” lines.
-	* Updated terminology wrt [=natural sizes=] and [=intrinsic sizes=].
+	* Renamed “intrinsic dimensions” to [=natural dimensions=] to avoid confusion with [=intrinsic sizes=].
 		(<a href="https://github.com/w3c/csswg-drafts/issues/4961">Issue 4961</a>)
 	* Copied over definition of computed <<image>> from [[css-images-3]].
 		(<a href="https://github.com/w3c/csswg-drafts/issues/4042">Issue 4042</a>)
+	* Explicitly allowed dithering in gradients.
+		(<a href="https://github.com/w3c/csswg-drafts/issues/4793">Issue 4793</a>)
 	* Assorted markup fixes, corrections to property syntaxes, inline issues, spelling corrections, example fixes and improvements, and minor editorial refinements.
 	* Shortened module title.