[css-color-4] more guidance on selecting color space for mixing

Author: svgeesus

css-color-4/Overview.bs

@@ -4395,12 +4395,18 @@ Interpolation</h2>
 <h3 id="interpolation-space">
 Color space for interpolation</h3>
 	Different color spaces may be more appropriate for each interpolation use case.
-	For example, Lab works well for gradients, and LCH works well for color mixing.
+	For example,
+	the perceptually uniform Lab works well for avoiding bunching up in gradients,
+	and the chroma-preserving LCH works well for avoiding greying out in color mixing,
+	while the linear-light XYZ is best for compositing
+	and gamma-encoded sRGB, which is neither linear light nor perceptually uniform,
+	will give overly dark mixes but is compatible with older Web content.
 	The host syntax may define what the default interpolation space should be for each case,
 	and optionally provide syntax for authors to override this default.
 
 	If the host syntax does not define what colorspace interpolation should take place in,
 	it defaults to Lab. In that case, user agents may handle interpolation
+	<!-- is that realy a MAY ? -->
 	between legacy sRGB color formats
 	(hex colors, named colors,
 	''rgb()'', ''hsl()'' or ''hwb()''