add ssl to mariadb centos 7 code example

Example: enabling ssl in mariadb server

cp /etc/letsencrypt/live/example.com/fullchain.pem /etc/mysql/fullchain.pem
openssl rsa -in /etc/letsencrypt/live/example.com/privkey.pem -out /etc/mysql/privkey.pem
chmod 444 /etc/mysql/fullchain.pem
chmod 400 /etc/mysql/privkey.pem
chown mysql:mysql /etc/mysql/fullchain.pem /etc/mysql/privkey.pem