pgsql: docs: Fix snapshot name in SET TRANSACTION docs.

docs: Fix snapshot name in SET TRANSACTION docs.

Commit 6c2003f8a1 changed the snapshot names mentioned in
SET TRANSACTION docs, however, there was one place that
the commit missed updating the name.

Back-patch to all supported versions.

Author: Japin Li
Reviewed-by: Fujii Masao
Discussion: https://postgr.es/m/MEYP282MB1669BD4280044501165F8B07B64F9@MEYP282MB1669.AUSP282.PROD.OUTLOOK.COM

Branch
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REL_12_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/e2744369db871bb6e998ea10fe1d7cdf68f57062

Modified Files
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doc/src/sgml/ref/set_transaction.sgml | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)