[css-color-5] RCS modern rgb & rgba syntax, w3c#8231

Author: svgeesus

css-color-5/Overview.bs

@@ -1023,13 +1023,12 @@ However, if calculations are done on missing values, ''none'' is treated as 0.
 The grammar of the [=modern color syntax=] ''rgb()'' and ''rgba()'' functions are extended as follows:
 
 <pre class='prod'>
-	<dfn>rgb()</dfn> = rgb( [ from <<color>> ]? 
+	<dfn><<modern-rgb-syntax>></dfn> = rgb( [ from <<color>> ]? 
 					[ <<number>> | <<percentage>> | none]{3} 
 					[ / [<<alpha-value>> | none] ]?  )
-	<dfn>rgba()</dfn> = rgba( [ from <<color>> ]? 
+	<dfn><<modern-rgba-syntax>></dfn> = rgba( [ from <<color>> ]? 
 					[ <<number>> | <<percentage>> | none]{3} 
 					[ / [<<alpha-value>> | none] ]?  )
-	<dfn>&lt;alpha-value></dfn> = <<number>> | <<percentage>>
 	</pre>