minor fixes to diagram needed

[VladimirAlexiev]

Hi @mgh128, not sure which (non-ontology) diagram you'll put in the spec: I'm looking at EPCIS-Ontology-alternativeVersion-2021-09-14r3.pdf

• "type" is missing from nodes where it's mandatory (the Event subclasses)
• EPCISDocument shows "id", should be just id
• Should we add ILMD?