curl --request POST \
  --url https://api.terminal49.com/v2/custom_field_definitions/{definition_id}/options \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: application/json' \
  --data '{}'

{
  "data": {
    "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "attributes": {
      "label": "<string>",
      "value": "<string>",
      "position": 123
    }
  },
  "links": {
    "self": "<string>"
  }
}