[css-flexbox-1][editorial] Fix title

Author: tabatkins

css-flexbox-1/Overview.bs

@@ -1276,7 +1276,7 @@ Flex Direction and Wrap: the 'flex-flow' shorthand</h3>
 	</div>
 
 <h3 id='order-property' oldids="propdef-order,order-accessibility,order-modified-document-order">
-Item Reordering: the 'order' property</h3>
+Reordering and Accessibility: the 'order' property</h3>
 
 	<a>Flex items</a> are, by default, displayed and laid out
 	in the same order as they appear in the source document,