Unable to specify NS TTL during domain creation

When creating a new domain (https://developers.digitalocean.com/documentation/v2/#create-a-new-domain), the API automatically creates NS records for `ns1.digitalocean.com`, `ns2.digitalocean.com` and `ns3.digitalocean.com`. It creates these records with a low TTL of `1800`, much lower than the generally recommended `86400` (which incidentally is what it creates them with if you create the domain via the Control Panel).

The call to create a domain via the API should allow the client to specify the TTL for the autogenerated NS records. Or, should allow the client to choose to disable the autogeneration of NS records so that they can be manually created using other API calls.

This is particularly frustrating when using the Terraform provider. To work around it, I'm having to use `provisioner "local-exec"` resources that call out to the API to fetch the ID's of the automatically generated NS records and update the TTL's to something more suitable.