Upgrade and downgrade instructions

To upgrade MailerQ from version < 5.6 to 5.6+

Debian/Ubuntu:

sudo apt update
sudo apt install -y mailerq
sudo mailerq --repair-database

CentOS/RHEL:

yum update
mailerq --repair-database

To downgrade MailerQ from version 5.6+ to 5.5

Debian/Ubuntu:

sudo apt-get install -y --allow-downgrades mailerq-5.5
sudo mailerq --repair-database

CentOS/RHEL:

yum remove mailerq-5.6
yum install mailerq-5.5
mailerq --repair-database