pgsql: docs: fix text by adding/removing parentheses

docs: fix text by adding/removing parentheses

Reported-by: Daisuke Higuchi

Author: Daisuke Higuchi, Erik Wienhold

Reviewed-by: Erik Wienhold

Discussion: /messages/by-id/CAEVT6c9FRQcFCzQ8AO=QoeQNA-w6RhTkfOUHzY6N2xD5YnBxhg@mail.gmail.com

Backpatch-through: master

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/e8bfad4ca842733b957c01e732ec009778f952cd

Modified Files
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doc/src/sgml/client-auth.sgml | 2 +-
doc/src/sgml/ltree.sgml | 2 +-
doc/src/sgml/trigger.sgml | 2 +-
3 files changed, 3 insertions(+), 3 deletions(-)