pgsql: Note that index_name in ALTER INDEX ATTACH PARTITION can be sche

Note that index_name in ALTER INDEX ATTACH PARTITION can be schema-qualified

Missed in 8b08f7d4820f; backpatch to all supported branches.

Reported-by: alvaro@datadoghq.com
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/172924785099.698.15236991344616673753@wrigleys.postgresql.org

Branch
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REL_13_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/fde796eea922a488593ceb94b93a18dd17e60463

Modified Files
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doc/src/sgml/ref/alter_index.sgml | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)