List alert fields

curl --request GET \
  --url https://api.rootly.com/v1/alert_fields \
  --header 'Authorization: Bearer <token>'

{
  "data": [
    {
      "id": "<string>",
      "attributes": {
        "name": "<string>",
        "kind": "<string>",
        "created_at": "<string>",
        "updated_at": "<string>",
        "slug": "<string>"
      }
    }
  ],
  "links": {
    "self": "<string>",
    "first": "<string>",
    "prev": "<string>",
    "next": "<string>",
    "last": "<string>"
  },
  "meta": {
    "current_page": 123,
    "next_page": 123,
    "prev_page": 123,
    "total_count": 123,
    "total_pages": 123,
    "next_cursor": "<string>"
  }
}