[css-color-5][editorial] Update legacy rgba RCS example to use commas

Author: svgeesus

css-color-5/Overview.bs

@@ -939,10 +939,10 @@ Relative color syntax is only applicable to the non-legacy RGB syntactic forms.
 
 <div class="example invalid">
 	For example, this attempt to use the rgba
-	<a>legacy color syntax</a> would be incorrect
+	<a>legacy color syntax</a> with commas would be incorrect
 
 	<pre>
-		rgba(from <span class="swatch" style="--color: darkblue"></span> darkblue 16 32 b / 0.5 )
+		rgba(from <span class="swatch" style="--color: darkblue"></span> darkblue 16, 32, b, 0.5 )
 	</pre>
 </div>