pgsql: doc: Fix incorrect wording for --file in pg_dump

doc: Fix incorrect wording for --file in pg_dump

The documentation stated that the directory specified by --file
must not exist, but pg_dump does allow for empty directories to
be specified and used.

Author: Daniel Gustafsson <daniel@yesql.se>
Reviewed-by: Bruce Momjian <bruce@momjian.us>
Discussion: https://postgr.es/m/534AA60D-CF6B-432F-9882-E9737B33D1B7@gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/07961ef86625be91e243f1dff8911cb1d70e443f

Modified Files
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doc/src/sgml/ref/pg_dump.sgml | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)