Обсуждение: pgsql: pg_upgrade: improve docs about extension upgrades

pg_upgrade:  improve docs about extension upgrades

The previous wording was unclear about the steps needed to upgrade
extensions, and how to update them after pg_upgrade.

Reported-by: Dave Cramer

Discussion: https://postgr.es/m/CADK3HHKawwbOcGwMGnDuAf3-U8YfvTcS8jqDv3UM=niijs3MMA@mail.gmail.com

Backpatch-through: 9.6

Branch
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REL9_6_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/763b95cecc747aa95161b7e13102f087aa5a6b21

Modified Files
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doc/src/sgml/ref/pgupgrade.sgml | 32 +++++++++++++++++++++-----------
1 file changed, 21 insertions(+), 11 deletions(-)