pgsql: Update release notes for releases 9.0.1, 8.4.5, 8.3.12, 8.2.18,

Update release notes for releases 9.0.1, 8.4.5, 8.3.12, 8.2.18, 8.1.22,
8.0.26, and 7.4.30.

Branch
------
REL9_0_STABLE

Details
-------
http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=9caf5a841b6231715a9612d97579b5b93e3c2322

Modified Files
--------------
doc/src/sgml/release-7.4.sgml | 101 +++++++++-
doc/src/sgml/release-8.0.sgml | 171 ++++++++++++++-
doc/src/sgml/release-8.1.sgml | 193 ++++++++++++++++-
doc/src/sgml/release-8.2.sgml | 257 +++++++++++++++++++++-
doc/src/sgml/release-8.3.sgml | 342 ++++++++++++++++++++++++++++-
doc/src/sgml/release-8.4.sgml | 491 ++++++++++++++++++++++++++++++++++++++++-
doc/src/sgml/release-9.0.sgml | 115 +++++++++-
7 files changed, 1640 insertions(+), 30 deletions(-)