pgsql: Doc: Generated column replication.

Doc: Generated column replication.

Commit 7054186c4e added the support to publish generated stored columns.
This patch adds detailed documentation for that feature.

Author: Peter Smith <smithpb2250@gmail.com>
Reviewed-by: Vignesh C <vignesh21@gmail.com>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Discussion: https://postgr.es/m/B80D17B2-2C8E-4C7D-87F2-E5B4BE3C069E%40gmail.com
Discussion: https://postgr.es/m/CAHut+PsYmAvKhUjA1AaR1rxLdeSBKiBko8wKyf4_H8nEEqDuOg@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/6252b1eaf82bb8db361341d1c8651e43b29be816

Modified Files
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doc/src/sgml/ddl.sgml                    |   1 +
doc/src/sgml/logical-replication.sgml    | 192 +++++++++++++++++++++++++++++++
doc/src/sgml/ref/create_publication.sgml |   5 +
3 files changed, 198 insertions(+)