[css-2023] Add RCS to cleared to ship

Author: svgeesus

css-2023/Overview.bs

@@ -873,6 +873,8 @@ Safe to Release pre-CR Exceptions</h2>
 		<li>The <a>color-mix()</a> function. [[!CSS-COLOR-5]]
 
 		<li>The <<color-interpolation-method>>, defined in [[!CSS-COLOR-4]] and used for interpolation of linear, radial and conic gradients. [[!CSS-IMAGES-4]]
+
+		<li>The [=relative color=] syntax, defined in [[!CSS-COLOR-5]]</li>
 	</ul>
 
 	The following features have been explicitly and retroactively cleared