pgsql: Some editorial work on the documentation of the current-date/time

Log Message:
-----------
Some editorial work on the documentation of the current-date/time
functions.

Modified Files:
--------------
pgsql/doc/src/sgml:
func.sgml (r1.322 -> r1.323)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/func.sgml.diff?r1=1.322&r2=1.323)