pgsql: Doc: Update the behavior of generated columns in Logical Replica

Doc: Update the behavior of generated columns in Logical Replication.

Commit 745217a051 misses updating the new behavior of generated columns in
logical replication at a few places.

Reported-by: Peter Smith, Ajin Cherian
Author: Vignesh C
Discussion: https://postgr.es/m/CALDaNm2JOO7szz9+uaQbjmgZOfzbM_9tAQdFF8H5BjkQeaJs0A@mail.gmail.com
Discussion: https://postgr.es/m/B80D17B2-2C8E-4C7D-87F2-E5B4BE3C069E@gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/5b0c46ea0932e3be64081a277b5cc01fa9571689

Modified Files
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doc/src/sgml/ddl.sgml                 | 5 +++--
doc/src/sgml/logical-replication.sgml | 4 +++-
2 files changed, 6 insertions(+), 3 deletions(-)