Log Message:
-----------
Document why 'cp -i </dev/null' is suggested for archive command.
Modified Files:
--------------
pgsql/doc/src/sgml:
backup.sgml (r2.144 -> r2.145)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/backup.sgml?r1=2.144&r2=2.145)