Fixes #1448. Docs error: on file-formats for RadioButton

docs/file-formats.html

@@ -5759,7 +5759,7 @@ RadioButton</h4>
 </tr>
 <tr>
 	<td>
-		&nbsp; checked = <span class="Non-literal"><span>false</span></span>
+		&nbsp; selected = <span class="Non-literal"><span>false</span></span>
 	</td>
 	<td>
 		[0..1]