loading oscar-corpus/OSCAR-2201  raises an error
## Describe the bug
load_dataset('oscar-2201', 'af')

raises an error:
Traceback (most recent call last):
  File "/usr/lib/python3.8/code.py", line 90, in runcode
    exec(code, self.locals)
  File "<input>", line 1, in <module>
  File "..python3.8/site-packages/datasets/load.py", line 1656, in load_dataset
    builder_instance = load_dataset_builder(
  File ".../lib/python3.8/site-packages/datasets/load.py", line 1439, in load_dataset_builder
    dataset_module = dataset_module_factory(
  File ".../lib/python3.8/site-packages/datasets/load.py", line 1189, in dataset_module_factory
    raise FileNotFoundError(
FileNotFoundError: Couldn't find a dataset script at .../oscar-2201/oscar-2201.py or any data file in the same directory. Couldn't find 'oscar-2201' on the Hugging Face Hub either: FileNotFoundError: Couldn't find file at https://raw.githubusercontent.com/huggingface/datasets/master/datasets/oscar-2201/oscar-2201.py


I've tried other permutations such as : 
oscar_22 = load_dataset('oscar-2201', 'af',use_auth_token=True)
oscar_22 = load_dataset('oscar-corpus/OSCAR-2201', 'af',use_auth_token=True)
oscar_22 = load_dataset('oscar-2201', 'af')
oscar_22 = load_dataset('oscar-corpus/OSCAR-2201')


with the same unfortunate result.


## Steps to reproduce the bug
oscar_22 = load_dataset('oscar-2201', 'af',use_auth_token=True)
oscar_22 = load_dataset('oscar-corpus/OSCAR-2201', 'af',use_auth_token=True)
oscar_22 = load_dataset('oscar-2201', 'af')
oscar_22 = load_dataset('oscar-corpus/OSCAR-2201')
# Sample code to reproduce the bug
```

## Expected results
loaded data

## Actual results
Traceback (most recent call last):
  File "/usr/lib/python3.8/code.py", line 90, in runcode
    exec(code, self.locals)
  File "<input>", line 1, in <module>
  File "..python3.8/site-packages/datasets/load.py", line 1656, in load_dataset
    builder_instance = load_dataset_builder(
  File ".../lib/python3.8/site-packages/datasets/load.py", line 1439, in load_dataset_builder
    dataset_module = dataset_module_factory(
  File ".../lib/python3.8/site-packages/datasets/load.py", line 1189, in dataset_module_factory
    raise FileNotFoundError(
FileNotFoundError: Couldn't find a dataset script at .../oscar-2201/oscar-2201.py or any data file in the same directory. Couldn't find 'oscar-2201' on the Hugging Face Hub either: FileNotFoundError: Couldn't find file at https://raw.githubusercontent.com/huggingface/datasets/master/datasets/oscar-2201/oscar-2201.py

## Environment info
<!-- You can run the command `datasets-cli env` and copy-and-paste its output below. -->
- `datasets` version: 2.3.2
- Platform: Linux-5.13.0-37-generic-x86_64-with-glibc2.29
- Python version: 3.8.10
- PyArrow version: 8.0.0
- Pandas version: 1.4.3

