Clarify wording of allowed roles for checkbox input with aria-pressed (#316)

port of #315 to implementation report

Author: patrickhlauke

results/implementation-results.html

@@ -1372,10 +1372,10 @@ <h2>Conformance Checker Rule Implementations</h2>
         <td>
           <p>
             Roles:
-            <code>button</code> (when used with <code>aria-pressed</code>),
             <code>menuitemcheckbox</code>,
             <code>option</code>
-            or <code>switch</code>.
+            or <code>switch</code>;
+            <code>button</code> if used with <code>aria-pressed</code>.
           </p>
           <p>
             Authors <em>SHOULD NOT</em> use the <code>aria-checked</code> attribute on <code>input type=checkbox</code> elements.