[css-color-4] Explain why one JND for Oklab is 0.02, not 2

Author: svgeesus

css-color-4/Overview.bs

@@ -5450,6 +5450,16 @@ CSS Gamut Mapping to an RGB Destination</h3>
 	For the Oklch color space,
 	one JND is is an Oklch difference of 0.02.
 
+	Note: In CIE Lab color space,
+	where the range of the Lightness component is 0 to 100,
+	using deltaE2000,
+	one JND is 2.
+	Because the range of Lightness in Oklab and Oklch
+	is 0 to 1,
+	using deltaEOK,
+	one JND is 100 times smaller.
+
+
 <h4 id="binsearch">
 Sample Pseudocode for the Binary Search Gamut Mapping Algorithm with Local MINDE</h4>