pgsql: Doc: clarify that DROP ... CASCADE is recursive.

Doc: clarify that DROP ... CASCADE is recursive.

Apparently that's not obvious to everybody, so let's belabor the point.

In passing, document that DROP POLICY has CASCADE/RESTRICT options (which
it does, per gram.y) but they do nothing (I assume, anyway).  Also update
some long-obsolete commentary in gram.y.

Discussion: <20160805104837.1412.84915@wrigleys.postgresql.org>

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/499787819309293f3d2cd7219aee334a0e7d5069

Modified Files
--------------
doc/src/sgml/ddl.sgml                           | 23 +++++++++++++++++------
doc/src/sgml/ref/alter_domain.sgml              |  4 +++-
doc/src/sgml/ref/alter_foreign_table.sgml       |  4 +++-
doc/src/sgml/ref/alter_table.sgml               |  4 +++-
doc/src/sgml/ref/drop_access_method.sgml        |  4 +++-
doc/src/sgml/ref/drop_aggregate.sgml            |  5 ++++-
doc/src/sgml/ref/drop_collation.sgml            |  4 +++-
doc/src/sgml/ref/drop_domain.sgml               |  4 +++-
doc/src/sgml/ref/drop_event_trigger.sgml        |  4 +++-
doc/src/sgml/ref/drop_extension.sgml            |  4 +++-
doc/src/sgml/ref/drop_foreign_data_wrapper.sgml |  6 ++++--
doc/src/sgml/ref/drop_foreign_table.sgml        |  3 ++-
doc/src/sgml/ref/drop_function.sgml             |  4 +++-
doc/src/sgml/ref/drop_index.sgml                |  4 +++-
doc/src/sgml/ref/drop_language.sgml             |  4 +++-
doc/src/sgml/ref/drop_materialized_view.sgml    |  4 +++-
doc/src/sgml/ref/drop_opclass.sgml              |  4 +++-
doc/src/sgml/ref/drop_operator.sgml             |  4 +++-
doc/src/sgml/ref/drop_opfamily.sgml             |  4 +++-
doc/src/sgml/ref/drop_owned.sgml                |  4 +++-
doc/src/sgml/ref/drop_policy.sgml               | 14 +++++++++++++-
doc/src/sgml/ref/drop_rule.sgml                 |  4 +++-
doc/src/sgml/ref/drop_schema.sgml               | 13 ++++++++++++-
doc/src/sgml/ref/drop_sequence.sgml             |  4 +++-
doc/src/sgml/ref/drop_server.sgml               |  4 +++-
doc/src/sgml/ref/drop_table.sgml                |  4 +++-
doc/src/sgml/ref/drop_transform.sgml            |  6 ++++--
doc/src/sgml/ref/drop_trigger.sgml              |  4 +++-
doc/src/sgml/ref/drop_tsconfig.sgml             |  4 +++-
doc/src/sgml/ref/drop_tsdictionary.sgml         |  4 +++-
doc/src/sgml/ref/drop_tsparser.sgml             |  4 +++-
doc/src/sgml/ref/drop_tstemplate.sgml           |  4 +++-
doc/src/sgml/ref/drop_type.sgml                 |  4 +++-
doc/src/sgml/ref/drop_view.sgml                 |  4 +++-
src/backend/parser/gram.y                       | 14 +++++++-------
35 files changed, 144 insertions(+), 48 deletions(-)