configure centos on docker code example

Example: install docker on centos

# First add repo to yum config manager
sudo yum install -y yum-utils
sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
# Use added repo to install and start docker
sudo yum install docker-ce docker-ce-cli containerd.io
sudo systemctl start docker
# Optional: Validate by run sample image 
sudo docker run hello-world