pgsql: Update 9.2 release notes to reflect commits to date.

Update 9.2 release notes to reflect commits to date.

I was unable to entirely resist the temptation to copy-edit related
entries, but will save most of that for a separate pass.

Branch
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REL9_2_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/3f9abab59021fff43dade76bfeea139ccbbb38dc

Modified Files
--------------
doc/src/sgml/release-9.2.sgml |  139 +++++++++++++++++++++++++++++++----------
1 files changed, 105 insertions(+), 34 deletions(-)