How to show fan-in jobs' results in response ("pending" and "failed" keys)
In cache entries of fan-in jobs we have keys `pending` and `failed`. For example, config-level `/parquet` response has the following format (only "parquet_files" key):
```python
{
    "parquet_files": [
        {
            "dataset": "duorc",
            "config": "ParaphraseRC",
            "split": "test",
            "url": "https://huggingface.co/datasets/duorc/resolve/refs%2Fconvert%2Fparquet/ParaphraseRC/duorc-test.parquet",
            "filename": "duorc-test.parquet",
            "size": 6136591
        },
       ... # list of parquet files
    ],
}
``` 
and for dataset-level it also has `pending` and `failed` keys:
```python
{
    "parquet_files": [
        {
            "dataset": "duorc",
            "config": "ParaphraseRC",
            "split": "test",
            "url": "https://huggingface.co/datasets/duorc/resolve/refs%2Fconvert%2Fparquet/ParaphraseRC/duorc-test.parquet",
            "filename": "duorc-test.parquet",
            "size": 6136591
        },
       ... # list of parquet files
    ],
    "pending": [],
    "failed": []
}
```
To me, undocumented `"pending"` and `"failed"` keys look a bit too technical and unclear.

What we can do:
* document what these keys mean
* don't document it but also for these kind of endpoints show only examples where all levels are specified (currently it's not like this). So, don't show examples that return `pending` and `failed` field.
* anything else? @huggingface/datasets-server 
How to show fan-in jobs' results in response ("pending" and "failed" keys): In cache entries of fan-in jobs we have keys `pending` and `failed`. For example, config-level `/parquet` response has the following format (only "parquet_files" key):
```python
{
    "parquet_files": [
        {
            "dataset": "duorc",
            "config": "ParaphraseRC",
            "split": "test",
            "url": "https://huggingface.co/datasets/duorc/resolve/refs%2Fconvert%2Fparquet/ParaphraseRC/duorc-test.parquet",
            "filename": "duorc-test.parquet",
            "size": 6136591
        },
       ... # list of parquet files
    ],
}
``` 
and for dataset-level it also has `pending` and `failed` keys:
```python
{
    "parquet_files": [
        {
            "dataset": "duorc",
            "config": "ParaphraseRC",
            "split": "test",
            "url": "https://huggingface.co/datasets/duorc/resolve/refs%2Fconvert%2Fparquet/ParaphraseRC/duorc-test.parquet",
            "filename": "duorc-test.parquet",
            "size": 6136591
        },
       ... # list of parquet files
    ],
    "pending": [],
    "failed": []
}
```
To me, undocumented `"pending"` and `"failed"` keys look a bit too technical and unclear.

What we can do:
* document what these keys mean
* don't document it but also for these kind of endpoints show only examples where all levels are specified (currently it's not like this). So, don't show examples that return `pending` and `failed` field.
* anything else? @huggingface/datasets-server 