Fix archive_command example
The given archive_command example didn't use %p or %f, which wouldn't
really work in practice.
Branch
------
REL8_3_STABLE
Details
-------
http://git.postgresql.org/pg/commitdiff/60817575f16331cc46f680584fed9ffc3bcb1dc4
Modified Files
--------------
doc/src/sgml/backup.sgml | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)