pgsql: Tweak the default behavior of psql's \dconfig.

Tweak the default behavior of psql's \dconfig.

\dconfig without an argument originally printed all parameters,
but it seems more useful to print only those parameters with
non-default settings. You can easily get the show-everything
behavior with "\dconfig *", but that output is unwieldy and
seems unlikely to be wanted very often.

Per suggestion from Christoph Berg.

Discussion: https://postgr.es/m/YlFQLzlPi4QD0wSi@msg.df7cb.de

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/5e70d8b5d18b0a71528dc6f11ade31a9d10e00cb

Modified Files
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doc/src/sgml/ref/psql-ref.sgml | 10 ++++++----
src/bin/psql/describe.c | 16 +++++++++++-----
2 files changed, 17 insertions(+), 9 deletions(-)