[css-values] lol, sin/cos range is -1 to 1, duh. Fixes w3c#4104.

Author: tabatkins

css-values-4/Overview.bs

@@ -2588,7 +2588,7 @@ Trigonometric Functions: ''sin()'', ''cos()'', ''tan()'', ''asin()'', ''acos()''
 	all represent the same value,
 	approximately ''.707''.)
 	They all represent a <<number>>;
-	''sin()'' and ''cos()'' will always return a number between 0 and 1,
+	''sin()'' and ''cos()'' will always return a number between -1 and 1,
 	while ''tan()'' can return any number between +∞ and −∞.
 	(See [[#calc-type-checking]] for details on how [=math functions=] handle ∞.)