Fix typo in aria-live description (w3c#822)

There was a typo in the description of aria-live="off";
"unless the used is..." should be "unless the user is...".

index.html

@@ -9961,7 +9961,7 @@ <h2>Definitions of States and Properties (all aria-* attributes)</h2>
 					</tr>
 					<tr>
 						<th class="value-name" scope="row"><strong class="default">off (default)</strong></th>
-						<td class="value-description">Indicates that updates to the region should not be presented to the user unless the used is currently focused on that region.</td>
+						<td class="value-description">Indicates that updates to the region should not be presented to the user unless the user is currently focused on that region.</td>
 					</tr>
 					<tr>
 						<th class="value-name" scope="row">polite</th>