[css-values-3] Update Changes list

Author: fantasai

css-values-3/Overview.bs

@@ -2229,6 +2229,15 @@ Changes</h2>
 	* Dropped the ''attr()'' function, since it was punted to Level 5.
 	* Specified serialization of empty urls to be <code>url("")</code>.
 		(<a href="https://github.com/w3c/csswg-drafts/issues/6447">Issue 6447</a>)
+	* Clarified that the [=font-relative lengths=] are calculated without text shaping.
+		(<a href="https://github.com/w3c/csswg-drafts/issues/5498">Issue 5498</a>)
+	* Added a definition for [=device pixel=].
+		(<a href="https://github.com/w3c/csswg-drafts/issues/7287">Issue 7287</a>)
+	* Cleaned up interaction of this specification and [[CSS-CASCADE-3]] in defining the [=CSS-wide keywords=].
+		(<a href="https://github.com/w3c/csswg-drafts/issues/7439">Issue 7439</a>)
+	* Removed definition of <<length-number>>.
+		(<a href="https://github.com/w3c/csswg-drafts/issues/2789">Issue 2789</a>)
+	* Editorial improvements.
 
 	Changes since the <a href="https://www.w3.org/TR/2019/CR-css-values-3-20190131/">31 January 2019 Candidate Recommendation</a> are: