pgsql: Update release notes for 8.3.1 and 8.2.7 releases.

Log Message:
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Update release notes for 8.3.1 and 8.2.7 releases.

Tags:
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REL8_3_STABLE

Modified Files:
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pgsql/doc/src/sgml:
release.sgml (r1.579 -> r1.579.2.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/release.sgml?r1=1.579&r2=1.579.2.1)