Retrieve all users.

Example response

[
  {
    "id": "ID",
    "first_name": "John",
    "last_name": "Doe",
    "nationality": {
      "iso": "BE",
      "description": "Belgian"
    },
    "club": {
      "id": "ID",
      "name": "demo name",
      "short_name": "DN",
      "country": "NL",
      "city": "Brussels",
      "email": "DN@atletiek.be"
    }
  }
]