pgsql: Doc: add a summary table to the CREATE POLICY docs.

Doc: add a summary table to the CREATE POLICY docs.

This table summarizes which RLS policy expressions apply to each
command type, and whether they apply to the old or new tuples (or
both), which saves reading through a lot of text.

Rod Taylor, hacked on by me. Reviewed by Fabien Coelho.

Discussion: https://postgr.es/m/CAHz80e4HxJShm6m9ZWFrHW=pgd2KP=RZmfFnEccujtPMiAOW5Q@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/87c2a17fee784c7e1004ba3d3c5d8147da676783

Modified Files
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doc/src/sgml/ref/create_policy.sgml | 104 +++++++++++++++++++++++++++++++++++-
1 file changed, 103 insertions(+), 1 deletion(-)