Fixed a typo.

[SVN r33129]

index.htm

@@ -463,7 +463,7 @@
 
                               <li>The overall error handling has been
                               improved. It is now possible to recover and
-                              continue after an error or warning was
+                              continue after an error or a warning was
                               issued.</li>
 
                               <li>Support for optional comment and/or full