pgsql: copy: update docs for FORCE_NULL and FORCE_NOT_NULL combination

copy:  update docs for FORCE_NULL and FORCE_NOT_NULL combination

Also update regression tests

Patch by Michael Paquier

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/7ec73783d88a743799b0c262f1235f772497fb1d

Modified Files
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contrib/file_fdw/file_fdw.c             |   10 ----------
contrib/file_fdw/input/file_fdw.source  |   10 ++++------
contrib/file_fdw/output/file_fdw.source |   11 +++--------
doc/src/sgml/ref/copy.sgml              |    7 +++++++
src/test/regress/expected/copy2.out     |   10 +++++-----
src/test/regress/sql/copy2.sql          |   10 +++++-----
6 files changed, 24 insertions(+), 34 deletions(-)