server/backup.sh: show file size at the end

See vdj#531.

server/backup.sh

@@ -44,4 +44,5 @@ else
         zip -r $filename web2py/applications/vidjil/databases/  "$DIR_RESULTS" $db_backup_file
 fi
 rm -f "$db_backup_file"
+ls -lh $filename
 echo $filename