[css-color-4][editorial] update changes

Author: svgeesus

css-color-4/Overview.bs

@@ -6309,6 +6309,9 @@ Changes</h2>
 </h3>
 
 <ul>
+	<!-- to 20 Oct 2022 -->
+	<li>Clarified a,b and C,h powerless at L=100% representing white.</li>
+	<li>Removed handwavy mention of L=400 which applies to hdr-CIELAB not CIE Lab</li>
 	<!-- to 18 Oct 2022  -->
 	<li>Consistent capitalization of Oklab and Oklch</li>
 	<li>Moved definitions of valid color, invalid color, out of gamut and in gamut to terminology section</li>