Upgrade and downgrade instructions

To upgrade MailerQ from version < 5.3 to 5.3+

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 5.3+ to 5.2

Debian/Ubuntu:

sudo apt-get install -y --allow-downgrades mailerq-5.2 mailerq=5.2.1
sudo mailerq --repair-database

CentOS/RHEL:

yum remove mailerq-5.3
yum install mailerq-5.2
mailerq --repair-database