Normalized revision date in document history.

Author: Paul Vinkenoog

src/docs/firebirddocs/nbackup.xml

@@ -1636,7 +1636,7 @@ ROWS 5</programlisting>
         <revision>
           <revnumber>1.4</revnumber>
 
-          <date>September 2014</date>
+          <date>18 Sep 2014</date>
 
           <authorinitials>MR</authorinitials>