add docker yum repository code example

Example 1: install docker centos 8

dnf config-manager --add-repo=https://download.docker.com/linux/centos/docker-ce.repo

Example 2: centos install docker-compose

sudo curl -L "https://github.com/docker/compose/releases/download/1.27.4/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose