Changed text to 'items-end'

Author: Robert Strauch

src/templates/docs/flexbox/index.html

@@ -453,7 +453,7 @@ <h4 class="f6 mb2 mt4">Start</h4>
             <h4 class="f6 mb2 mt4">End</h4>
 
             <p class="measure f5 lh-copy">
-              Pack items from the end with <code>items-center</code>
+              Pack items from the end with <code>items-end</code>
             </p>
 
             <div class="flex flex-wrap">