Add schema version to Record Metadata properties

It was brought up, that it would be useful to document in the record metadata the schema version (e.g. 1.0, 1.1) according to which the record was mapped in. We suggest to add this property to "Record Metadata" in the schema specification and when a JSON schema for record metadata exists consequenty also there.

ID	property	description	OB	OCC	value constraints	example
8	schemaVersion	The schema version applied to the record.	M or A	1	type:string	1.0