Unclear how hugo mod npm pack works

[willfaught]

hugoDocs/content/en/commands/hugo_mod_npm_pack.md

Lines 12 to 21 in 36dd548

	Prepares and writes a composite package.json file for your project.
	On first run it creates a "package.hugo.json" in the project root if not already there. This file will be used as a template file
	with the base dependency set.
	This set will be merged with all "package.hugo.json" files found in the dependency tree, picking the version closest to the project.
	This command is marked as 'Experimental'. We think it's a great idea, so it's not likely to be
	removed from Hugo, but we need to test this out in "real life" to get a feel of it,
	so this may/will change in future versions of Hugo.

It's unclear from this:

• That it creates project.json (PJ) if it doesn't exist
• What's in PJ or package.hugo.json (PHJ) if they're created
  • Also why is comments there? Why is an empty devDeps there?
• What's in PHJ if it's created and PJ exists
• What's in PJ if it's created and PHJ exists
• What happens if PJ and PHJ exist and don't match
• What happens to PJ if PHJ is updated, or vice versa
• If you should check in PHJ