[css-color-5] Update explanatory prose which still limited color-mix to two. #11530

Author: svgeesus

css-color-5/Overview.bs

@@ -209,10 +209,11 @@ Mixing Colors: the ''color-mix()'' Function {#color-mix}
 	and two colors with visually different lightness,
 	like yellow and blue, can have the same HSL lightness).
 
-	To meet this need, the color-mix() function takes two <<color>> specifications
+	To meet this need, the color-mix() function takes 
+	a list of one or more <<color>> specifications
 	and returns the result of mixing them,
 	in a given <<color-space>>,
-	by a specified amount.
+	in the specified amounts.
 
 
 <pre class='prod'>