Improve "Discriminator object" section of the OAS specification.
Changed misleading specification (used term list referring to an object)
#2157: Update schema to validate refs in headers of encoding objects
Github Issue Template with "Spec Issues Only" Advisory
actions: reinstate validation of schemas and examples, fixes #1739
Correct file extension on Alternative Schema Object
ProTip! Updated in the last three days: updated:>2020-06-30.