pgsql: doc: fix typo in release notes - Mailing list pgsql-committers

doc:  fix typo in release notes

Backpatch through 8.4

Per suggestion by Amit Langote

Branch
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REL9_2_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/5fbed6b1e1f9e7145679a9f90b5f8b6587f9cc19

Modified Files
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doc/src/sgml/release-8.4.sgml |    4 ++--
doc/src/sgml/release-9.0.sgml |    4 ++--
doc/src/sgml/release-9.1.sgml |    4 ++--
doc/src/sgml/release-9.2.sgml |    4 ++--
4 files changed, 8 insertions(+), 8 deletions(-)