Fix an error in documentation of date/time prompt section.

Thanks to Puneeth Chaganti <punchagan@gmail.com> for this patch.

doc/org.texi

@@ -5137,8 +5137,8 @@ in @b{bold}.
 2/5/3         --> 2003-02-05
 14            --> @b{2006}-@b{06}-14
 12            --> @b{2006}-@b{07}-12
-2/5           --> @b{2003}-02-05
-Fri           --> nearest Friday (defaultdate or later)
+2/5           --> @b{2007}-02-05
+Fri           --> nearest Friday (default date or later)
 sep 15        --> @b{2006}-09-15
 feb 15        --> @b{2007}-02-15
 sep 12 9      --> 2009-09-12