Document various internal plugin output as harmless.

i.e. EDSM doesn't accept Ring data via its API. We don't want to *stop* sending such in case EDSM starts wanting it. So we need to document that:

- [x] `EDSM 402 Item unknown {"Periapsis": 0.0,"_systemCoordinates": [-33300.0,19.5625,3139.5],"BodyName": "Byeia Thoea JI-K c8-0 4 A Ring","...`

is harmless.

There'll possibly be other examples of this, including for the Inara API.

No file, test, or entry point is named. Review the checked EDSM 402 Ring-data example and locate the project's existing documentation for plugin or API output, then check for comparable Inara examples. The issue is done when harmless responses are documented without disabling the existing sends.

Written by the indexing model from the issue text.