[css-ui-4] Clarify author requirements on cursor:pointer

Closes #1936

Author: frivoal

css-ui-4/Overview.bs

@@ -760,6 +760,8 @@ Values have the following meanings:
 		via the <a lt="User Agent Origin">UA stylesheet</a>,
 		using a normal (i.e. not <a>!important</a>) declaration.
 
+		Authors should use pointer on links and may use on other interactive elements.
+
 		<dt style="cursor:progress"><dfn>progress</dfn>
 		<dd>
 			A progress indicator.  The program is performing some processing,
@@ -2147,6 +2149,7 @@ the following normative changes have been made:
 	<li>Changed the requirement that the ''cursor/text'' cursor matches the writing mode from MAY to MUST
 	<li>The definition of the appearance property has been significantly reworked to make the design compatible with existing web content
 	<li>The logic that mapped ''user-select: auto'' to various values at computed value time has been changed to used value time
+	<li>Clarify Author requirements on the ''cursor: pointer'' value
 </ul>
 
 <h3 id=changes-22-09-2015 class=no-num>Changes from the