Can I load in list of list of dict format? 
Thanks for reporting, @LZY-the-boys.

Could you please give more details about what is your intended dataset structure? What are the names of the columns and the value of each row?

Currently, the JSON-Lines format is supported:
- Each line correspond to one row of the dataset
- Each line is composed of one JSON object, where the names are the names of the columns, and the values are the values for the row-column pair.
### Feature request

my jsonl dataset has following format:
```
[{'input':xxx, 'output':xxx},{'input:xxx,'output':xxx},...]
[{'input':xxx, 'output':xxx},{'input:xxx,'output':xxx},...]
```

I try to use `datasets.load_dataset('json', data_files=path)` or `datasets.Dataset.from_json`, it raises
```
  File "site-packages/datasets/arrow_dataset.py", line 1078, in from_json
    ).read()
  File "site-packages/datasets/io/json.py", line 59, in read
    self.builder.download_and_prepare(
  File "site-packages/datasets/builder.py", line 872, in download_and_prepare
    self._download_and_prepare(
  File "site-packages/datasets/builder.py", line 967, in _download_and_prepare
    self._prepare_split(split_generator, **prepare_split_kwargs)
  File "site-packages/datasets/builder.py", line 1749, in _prepare_split
    for job_id, done, content in self._prepare_split_single(
  File "site-packages/datasets/builder.py", line 1892, in _prepare_split_single
    raise DatasetGenerationError("An error occurred while generating the dataset") from e
datasets.builder.DatasetGenerationError: An error occurred while generating the dataset
```

### Motivation

I wanna use features like `Datasets.map` or `Datasets.shuffle`, so i need the dataset in memory to be `arrow_dataset.Datasets` format

### Your contribution

PR