describeRoute response configuration should allow reference

[ngraef]

The following gives a TypeScript error complaining about $ref not being a know property:

describeRoute({
  responses: {
    401: { $ref: '#/components/responses/401' }
  }
})

However, this is valid according to the OpenAPI spec, and it works as expected at runtime.

The type definition for DescribeRouteOptions["responses"][code:string] should allow a reference object.