Update doc

docs/source/image_load.mdx

@@ -98,6 +98,8 @@ Your `metadata.jsonl` file must have a `file_name` column which links image file
 {"file_name": "0003.png", "additional_feature": "This is a third value of a text feature you added to your images"}
 ```
 
+It may be more convenient to specify metadata in CSV for simple tasks. In that case, use `metadata.csv` as the name of the metadata file.
+
 <Tip>
 
 If metadata files are present, the inferred labels based on the directory name are dropped by default. To include those labels, set `drop_labels=False` in `load_dataset`.
@@ -106,12 +108,13 @@ If metadata files are present, the inferred labels based on the directory name a
 
 ### Image captioning
 
-Image captioning datasets have text describing an image. An example `metadata.jsonl` may look like:
+Image captioning datasets have text describing an image. An example `metadata.csv` may look like:
 
 ```jsonl
-{"file_name": "0001.png", "text": "This is a golden retriever playing with a ball"}
-{"file_name": "0002.png", "text": "A german shepherd"}
-{"file_name": "0003.png", "text": "One chihuahua"}
+file_name,text
+0001.png,This is a golden retriever playing with a ball
+0002.png,A german shepherd
+0003.png,One chihuahua
 ```
 
 Load the dataset with `ImageFolder`, and it will create a `text` column for the image captions: