curl --request GET \
  --url http://localhost:8000/v1/document-types/{code} \
  --header 'Authorization: Bearer <token>'

{
  "code": "<string>",
  "name": "<string>",
  "category": "<string>",
  "schema_version": "<string>",
  "fields": [
    {
      "field_name": "<string>",
      "field_type": "<string>",
      "is_nullable": true,
      "description": "<string>",
      "pattern": "<string>",
      "hints": [
        "<string>"
      ]
    }
  ],
  "validations": [
    {
      "name": "<string>",
      "message": "<string>",
      "formula": "<string>",
      "tolerance": 123
    }
  ],
  "description": "<string>"
}