[css-ui-3] Clarify computed values for outline-color the same way as for caret-color

Relates to #741: same ambiguity on a different property

Author: frivoal

css-ui/Overview.bs

@@ -333,7 +333,8 @@ Applies to: all elements
 Inherited: no 
 Percentages: N/A 
 Media: visual 
-Computed value: The computed value for ''invert'' is ''invert''. For <<color>> values, the computed value is as defined for the [[!CSS3COLOR]] 'color' property. 
+Computed value: The computed value for ''invert'' is ''invert''.
+ 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>
 
@@ -1482,7 +1483,7 @@ 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.
+	<li>Clarify by reference to [[CSS-COLOR-4]] how computed values are handled for caret-color and outline-color.
 	<li>Mark 'caret-color' as no longer at risk, since there are two implementations.
 	<li>Constraints on the shape of the outline when <a href="#negative-offset">negative values</a> are used for the 'outline-offset' property
 	    where changed from being expressed with MUST to SHOULD.