[css-values-5] Delete outdated note.

Author: fantasai

css-values-5/Overview.bs

@@ -1165,10 +1165,6 @@ Interpolated Property Values: the ''mix()'' notation</h3>
 	to interpolate the corresponding property declarations from a set of keyframes,
 	allowing for more complex interpolation curves.
 
-	Note: This [=functional notation=] uses semicolons to separate arguments
-	rather than the more typical comma
-	because the values themselves can contain commas.
-
 	For the standard [=mix notation=] variant,
 	if the two <<whole-value>>s being interpolated by ''mix()''
 	are [=interpolation|interpolable=]