pgsql: Slight adjustments to xml documentation to reflect functionality

Log Message:
-----------
Slight adjustments to xml documentation to reflect functionality just
added.

Modified Files:
--------------
pgsql/doc/src/sgml:
datatype.sgml (r1.182 -> r1.183)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/datatype.sgml.diff?r1=1.182&r2=1.183)