pgsql: doc: clarify handling of time zones with "time with time zone"

doc: clarify handling of time zones with "time with time zone"

Reported-by: davecramer@postgres.rocks

Discussion: /messages/by-id/168451942371.714.9173574930845904336@wrigleys.postgresql.org

Backpatch-through: 11

Branch
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REL_16_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/430f4497b02f3536b190cf5dca5da564eea151f4

Modified Files
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doc/src/sgml/datatype.sgml | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)