ZencoderOutput.min_size does not correspond to the documentation

According to the [documentation](https://app.zencoder.com/docs/api/encoding/conditional-outputs/min-size) this parameter should be passed as follows
`
{
  "outputs": [
    {
      "skip": {
        "min_size": "640x480"
      }
    }
  ]
}
`

But it is sending this way
`
{
  "outputs": [
    {
      "min_size": "640x480"
    }
  ]
}
`
