Docs indicate that `API` is a valid kind - schema does not

[RyPeck]

The docs for Definition Schema V3.0 indicate that API is a valid kind - but the schema does not.

https://docs.datadoghq.com/software_catalog/service_definitions/v3-0/#schema-overview

- kind field is new and defines the type of component: service, queue, datastore, system, or API

[mikejonestechno]

Works for me in a entity.datadog.yaml file. DD successfully imported from github and appears in the API section of system catalog.

apiVersion: v3
kind: api
... other properties here ...
spec:
  type: openapi