Fix(doc): clarify data loading for local datasets and splitting samples (#2726) [skip ci]

* fix(doc): remove incorrect json dataset loading method

* fix(doc): clarify splitting only happens in completion mode

* fix: update local file loading on config doc

* fix: typo

docs/dataset_loading.qmd

@@ -54,7 +54,7 @@ datasets:
 
 #### Files
 
-Usually, to load a JSON file, you would do something like this:
+To load a JSON file, you would do something like this:
 
 ```python
 from datasets import load_dataset
@@ -66,20 +66,12 @@ Which translates to the following config:
 
 ```yaml
 datasets:
-  - path: json
-    data_files: /path/to/your/file.jsonl
-```
-
-However, to make things easier, we have added a few shortcuts for loading local dataset files.
-
-You can just point the `path` to the file or directory along with the `ds_type` to load the dataset. The below example shows for a JSON file:
-
-```yaml
-datasets:
-  - path: /path/to/your/file.jsonl
+  - path: data.json
     ds_type: json
 ```
 
+In the example above, it can be seen that we can just point the `path` to the file or directory along with the `ds_type` to load the dataset.
+
 This works for CSV, JSON, Parquet, and Arrow files.
 
 ::: {.callout-tip}