This is so in that document because the proposed procedure is to install the docker folder on a separate drive from the operating system. The reasons are explained in the document a little earlier.
If you want to keep the default path /var/lib/docker you don't need to reinstall docker.
It all depends on what you want to configure and how you want to do it.
Yes...that's why I was letting Vitaman know how to set the Docker folder.
That user asked how to set the Docker folder as directed in OMV Docker guide.
( RE: omv-extras 6.3 / openmediavault-compose 6.7 )
As you recall, we used to do that before installing the OMV-compose plugin to ensure Docker would use the specified folder.
Now we do it after installing the plugin...but before actually installing Docker.
Of course, the new instructions show that screenshot and the steps to do this, but I didn't want to just RTFM my response.
You guys are pretty patient. Appreciate it.