pgsql: Call SET varaiables "configuration_parameter"s in the

Log Message:
-----------
Call SET varaiables "configuration_parameter"s in the documentation.

Modified Files:
--------------
pgsql/doc/src/sgml/ref:
alter_role.sgml (r1.4 -> r1.5)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/alter_role.sgml.diff?r1=1.4&r2=1.5)
alter_user.sgml (r1.40 -> r1.41)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/alter_user.sgml.diff?r1=1.40&r2=1.41)
reset.sgml (r1.29 -> r1.30)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/reset.sgml.diff?r1=1.29&r2=1.30)
set.sgml (r1.87 -> r1.88)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/set.sgml.diff?r1=1.87&r2=1.88)