Now you need to get this command to run each time the mac starts. So you need to edit a configuration file which is read each time the machine boots, in this case the file is named rc.local and is in the /etc folder (my server runs on a raspberry pi so it might be different for you).
Alternately there is the crontab -e command which will also open up a file you can edit, same as the rc.local file.
The Documentation is correct… as is @877’s description. It is just down to the methods used to run the command.
Upon entering the command in the Terminal window (CLI) the ending & allows a “separate process” that keeps the Server running in the background, instead of stopping when the CLI window is closed… but it will not automatically run upon boot.
But by putting that same command (with the &) into the rc.local file or using crontab, etc. then it automatically runs that same command each and every time the RPi boots, so you don’t have to type it.