[css-ui-3] Disambiguate the caret-color computed values

Closes w3c#741

Author: frivoal

css-ui/Overview.bs

@@ -1263,7 +1263,7 @@ Inherited: yes
 Percentages: N/A 
 Media: interactive 
 Computed value: The computed value for ''caret-color/auto'' is ''caret-color/auto''.
- For <<color>> values, the computed value is as defined for the [[!CSS3COLOR]] 'color' property. 
+ For <<color>> values, see <a>resolving color values</a> in [[!CSS-COLOR-4]].
 Animation Type: <a href="https://drafts.csswg.org/css3-transitions/#animtype-color">color</a> 
 </pre>
 
@@ -1539,6 +1539,7 @@ This appendix describes changes from the
 	    for compatibility with level 4.
 	<li>Make the 'caret-color' property apply to all elements,
 	    so that it can also influence things like the navigation caret.
+	<li>Clarify by reference to [[CSS-COLOR-4]] how computed values are handled for caret-color.
 </ul>
 
 <h2 class="no-num" id="security-privacy-considerations">Appendix C. Considerations for Security and Privacy</h2>