Feature Request: Exclude file in kaggle dataset

IMO, there should be a way to exclude certain files/folders when upload the dataset.

The exclude list can be list under `dataset-metadata.json`

For example,
```
{
"title": "INSERT_TITLE_HERE",
"id": "dattran2346/INSERT_SLUG_HERE",
"licenses": [
{
"name": "CC0-1.0"
}
]
"exclude: [
"checkpoints/*"
]
}
```

For my case, I currently want to wrap my code inside a dataset and upload it to run on kaggle kernel but I don't want to include my experiment checkpoints.

Hope other user find this feature useful.