Include latest versions of Docker

[rohitsakala]

When I look at docs of building docker, I only 18.x.x version but the latest version of docker is 20.x.x. Can you please update your docs for installing latest versions of docker.

Thanks

[cwsolee]

I'm not sure which doc you're referring to but you can find latest info. from here https://www.ibm.com/community/z/open-source-software/