[css-fonts-4] remove now-invalid example. Fix w3c#6877

Author: svgeesus

css-fonts-4/Overview.bs

@@ -6229,11 +6229,6 @@ Animation type: discrete
 	</pre>
 </div>
 
-<div class="example">When color is not supported at all, select the monochrome glyphs rather than rendering the colored glyphs in monochrome:
-	<pre>@media not (color) {
-		font-palette: none;
-	}</pre>
-</div>
 
 Issue: Add more examples and pictures.