pgsql: doc: mention "bloom" as a possible index access method

doc: mention "bloom" as a possible index access method

Also remove USING erroneously added recently.

Reported-by: Jeff Janes

Discussion: /messages/by-id/CAMkU=1zhCpC7hottyMWM5Pimr9vRLprSwzLg+7PgajWhKZqRzw@mail.gmail.com

Backpatch-through: 10

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/dd03dfeb3bc952818a34aaee30c31d491190aa21

Modified Files
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doc/src/sgml/indices.sgml | 3 ++-
doc/src/sgml/ref/create_index.sgml | 17 +++--------------
2 files changed, 5 insertions(+), 15 deletions(-)