Move some properties from "required" to "supported" on slider role

Addresses #860

index.html

@@ -6976,8 +6976,6 @@ <h5>Presentational Roles Conflict Resolution</h5>
 						<th class="role-required-properties-head">Required States and Properties:</th>
 						<td class="role-required-properties">
 							<ul>
-								<li><pref>aria-valuemax</pref></li>
-								<li><pref>aria-valuemin</pref></li>
 								<li><pref>aria-valuenow</pref></li>
 							</ul>
 						</td>
@@ -6988,6 +6986,8 @@ <h5>Presentational Roles Conflict Resolution</h5>
 							<ul>
 								<li><pref>aria-orientation</pref></li>
 								<li><pref>aria-readonly</pref></li>
+								<li><pref>aria-valuemax</pref></li>
+								<li><pref>aria-valuemin</pref></li>
 							</ul>
 						</td>
 					</tr>
@@ -7021,7 +7021,6 @@ <h5>Presentational Roles Conflict Resolution</h5>
 							Default for <pref>aria-orientation</pref> is <code class="default">horizontal</code>. <br/>
 							Default for <pref>aria-valuemin</pref> is <code class="default">0</code>. <br/>
 							Default for <pref>aria-valuemax</pref> is <code class="default">100</code>. <br/>
-							Default for <pref>aria-valuenow</pref> is half way between <code class="default">aria-valuemax</code> and <code class="default">aria-valuemin</code>.
 						</td>
 					</tr>
 				</tbody>