NEWS: Close <li> tag properly

Not closing the <li> tag on a separate line causes the plain
text version of the file to have no empty line between entries.

docs/news.html.in

@@ -32,7 +32,8 @@
       <li><strong>Improvements</strong>
         <ul>
           <li>virsh: Add support for passing an alternative persistent XML
-          to migrate command</li>
+          to migrate command
+          </li>
           <li>vhostuser: Allow hotplug of multiqueue devices
           </li>
           <li>NEWS: Switch to an improved format<br/>