Mention support by experimental lexmark backend.

unsupported/dell-a920.html

@@ -33,6 +33,10 @@
     <p>
     </p>
     <h2>Comments</h2>
+    <p>
+      The lexmark backend in <em>experimental</em> CVS has support for this
+      scanner in color mode, 75 dpi.
+    </p>
     <p>
       All-in-one. Probably relabelled Lexmark 1150. At least printer driver for
       Lexmark 1150 works. However, the vendor id is Dell.