It's simply the standard CLI commands...
You prep your .JSON file for the type of upgrade destination, and then you enter the command-line parameters. In this case, there is nothing unusual...
vcsa-deploy upgrade --accept-eula --acknowledge-ceip --log-dir=<path> <JSON FIle with path>
Nothing interesting. Thought I do typically add the verbose flag as well (--verbose)...
During the process, you see the occasional 'failed normalizing ip: <FQDN> of the vCenter or PSC'
I don't see it in any of our documentation, or posted anywhere else.