[css-color] add note explaining a reasonable range for C in lch() to the

          spec

Author: svgeesus

css-color/Overview.bs

@@ -195,6 +195,9 @@ The RGB functions: ''rgb()'' and ''rgba()''</h3>
 	For this reason, values outside of the 0%-100% range are allowed,
 	but are clamped to the device's gamut.)
 
+	<p class="issue">The transfer function is undefined outside the range 0% to 100%.</p>
+	
+
 	The final argument, the <<alpha-value>>, specifies the alpha of the color.
 	If given as a <<number>>, the useful range of the value is ''0''
 	(representing a fully transparent color)
@@ -1709,8 +1712,8 @@ The identifier is either one of the predefined spaces
 	<p class="issue">Further define a fallback color, as decided at San Francisco. 
 		Can be an sRGB fallback or indeed another color() function.</p>
 
-	<p class="issue">Need to add choice of quoted string or number+, to allow f
-		or named color profiles.</p>
+	<p class="issue">Need to add choice of quoted string or number+, to allow
+		for named color profiles.</p>
 
 <h3 id="predefined">Predefined colorspaces: DCI P3 and Rec.2020.</h3>
 
@@ -1733,6 +1736,9 @@ The DCI P3 [[!DCI-P3]] colorspace has the following characteristics:
 	(particularly for the transfer function and viewing conditions).
 </p>
 
+<p class="issue">DCI transfer function is gamma 1/2.6 while Apple P3 displays use gamma 1/2.2.</p>
+
+
 The ITU Rec.2020 [[!Rec.2020]] 
 	colorspace has the following characteristics:
 
@@ -1766,6 +1772,8 @@ although in practice all but the first step are linear calculations and can be c
 	<li>Convert D50-adapted XYZ to Lab
 </ol>
 
+<p class="issue">Canvas proposes adding a 16bit half-float linear 2020 space</p>
+
 <h4 id="lab-to-predefined">Converting Lab to predefined colorspaces</h4>
 
 Conversion from Lab to p3 or rec2020 also requires multiple steps, and again in practice all