Current json output example is not generically applicable to all checks

[mpacer]

When running on the PEP-0008.txt text, none of the output mentions any source for any of the advice.

Is that example out of date from the pre-"redesign module structure to avoid apparent endorsement" days? Is it actually out of date?

[mpacer]

note: proselint --demo --json | grep "source" returns nothing