pgsql: doc: improve tablespace example query and link to helper funcs.

doc: improve tablespace example query and link to helper funcs.

Reported-by: Agustín

Discussion: /messages/by-id/172609721070.1128084.6724666076293146476@wrigleys.postgresql.org

Backpatch-through: master

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/e1a76db1a880c2e80ae96c40a31b0ee589e06562

Modified Files
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doc/src/sgml/manage-ag.sgml | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)