In the interests of offering listeners at least partial data about the
location of a codex entry we will allow `BodyName` to be set from
Status.json, but without `BodyID` from the Journal if it is not
available.
Currently if Status.json BodyName doesn't match that from the journal we
specify sending neither it nor the BodyID. We could still send the
BodyName **from Status.json** as that's better than no data about the
location.
* Add README-EDDN-schemas.md to hold general documentation for reference
by other files such as...
* Update codexentry-README.md to reference the general documentation.
* Add BodyID and BodyName as optional keys.
* Add `description` at top-level pointing to README documentation.
* Add schema-specific README to document what should be (in|ex)cluded
from data, and how to obtain such from Journals etc.