[css-color-5] Clarify serialization for srgb-linear, hsl(), hwb() & xyz. Fix w3c#6860

Author: Chris Lilley

css-color-5/Overview.bs

@@ -2361,15 +2361,15 @@ is the same as that specified in
 	</tr>
 	<tr>
 		<td>srgb-linear</td>
-		<td>color(srgb r g b)</td>
+		<td>color(srgb r g b) <a href="#fn1">¹</a></td>
 	</tr>
 	<tr>
 		<td>hsl</td>
-		<td>hsl(h s l)</td>
+		<td>hsl(h s l) <a href="#fn2">²</a></td>
 	</tr>
 	<tr>
 		<td>hwb</td>
-		<td>hwb(h w b)</td>
+		<td>hwb(h w b) <a href="#fn3">³</a></td>
 	</tr>
 	<tr>
 		<td>xyz-d65</td>
@@ -2381,7 +2381,7 @@ is the same as that specified in
 	</tr>
 	<tr>
 		<td>xyz</td>
-		<td>color(xyz-d65 x y z)</td>
+		<td>color(xyz-d65 x y z) <a href="#fn4">⁴</a></td>
 	</tr>
 	<tr>
 		<td>lab</td>
@@ -2401,6 +2401,17 @@ is the same as that specified in
 	</tr>
 </table>
 
+<dl>
+	<dt id="fn1">¹</dt>
+	<dd>After conversion back to gamma-encoded form</dd>
+	<dt id="fn2">²</dt>
+	<dd>''hsl()'' will then serialize as ''rgb()'' or ''rgba()''</dd>
+	<dt id="fn3">³</dt>
+	<dd>''hwb()'' will then serialize as ''rgb()'' or ''rgba()''</dd>
+	<dt id="fn4">⁴</dt>
+	<dd>Because ''xyz'' is just an alias for ''xyz-d65''</dd>
+</dl>
+
 <div class="example">
 	The result of this color mixture
 	<pre>color-mix(in lch, peru 40%, palegoldenrod)</pre>