add redis database configuration

[chri2]

YunoHost/issues#2266

without this rspamd does not use the redis database

[Tagadda]

You'll have to edit this file too

yunohost/hooks/conf_regen/31-rspamd

Lines 5 to 16 in 2bf2956

	do_pre_regen() {
	pending_dir=$1
	cd /usr/share/yunohost/conf/rspamd
	install -D -m 644 metrics.local.conf \
	"${pending_dir}/etc/rspamd/local.d/metrics.conf"
	install -D -m 644 dkim_signing.conf \
	"${pending_dir}/etc/rspamd/local.d/dkim_signing.conf"
	install -D -m 644 rspamd.sieve \
	"${pending_dir}/etc/dovecot/global_script/rspamd.sieve"
	}