[css-color-4] Describe increasing and decreasing when 0/360 is passed

Author: svgeesus

css-color-4/Overview.bs

@@ -4960,6 +4960,8 @@ Hue Interpolation</h3>
 	Hue angles are interpolated so that, 
 	as they progress from the first color to the second, 
 	the angle is always <em>increasing</em>.
+	If the angle increases to 360 it is reset to zero,
+	and then continues increasing.
 
 	Depending on the difference between the two angles, 
 	this will either look the same as <em>shorter</em> or as <em>longer.</em>
@@ -4997,6 +4999,8 @@ Hue Interpolation</h3>
 	Hue angles are interpolated so that, 
 	as they progress from the first color to the second, 
 	the angle is always <em>decreasing</em>.
+	If the angle decreases to 0 it is reset to 360,
+	and then continues decreasing.
 
 	Depending on the difference between the two angles, 
 	this will either look the same as <em>shorter</em> or as <em>longer.</em>