pgsql: Update release notes for latest commits.

Update release notes for latest commits.

In addition, correct the entry for pg_object_description, and some other
minor cleanup.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/ab1ef8e4448d276d65ecd02bebc03c03854c7200

Modified Files
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doc/src/sgml/release-9.1.sgml |   61 +++++++++++++++++++++++++++++++++--------
1 files changed, 49 insertions(+), 12 deletions(-)