Clarify DNS query record type / class type source data

[miwent]

The use of query record type / class type may not be clear. DNS requests will include a record type, but the answers will also include a record type - the answers may include other record types than what was requested, such as a CNAME response.

Clarify that the record request type should prefer the request record/class type where the log source provides the query record/class types, but that if absent the response record/class types can be used.