pgsql: doc, pg_upgrade: add vacuumdb w/ tips for generating quick stats

doc, pg_upgrade: add vacuumdb w/ tips for generating quick stats

Reported-by: Magnus Hagander

Discussion: /messages/by-id/CABUevEwGBY-W7EkTbjMY1rC+mmRL3fMrnX6YaUkcr+7o9PSa3w@mail.gmail.com

Backpatch-through: master

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/c0fcf077708c99d64c86087eb567999cb85848e0

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