pgsql: doc: \copy can get data values \. and end-of-input confused

doc: \copy can get data values \. and end-of-input confused

Reported-by: Svante Richter

Discussion: /messages/by-id/fcd57e4-8f23-4c3e-a5db-2571d09208e2@beta.fastmail.com

Backpatch-through: 11

Branch
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REL_11_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/930bc76bec1021c9ab8c8cb41cc08d598c2e26d8

Modified Files
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doc/src/sgml/ref/psql-ref.sgml | 4 ++++
src/bin/psql/copy.c | 1 +
2 files changed, 5 insertions(+)