docs(datasets) Add info about dataset availability to FDS docs (#3902)

datasets/doc/source/index.rst

@@ -67,10 +67,14 @@ Main features
 -------------
 Flower Datasets library supports:
 
-- **downloading datasets** - choose the dataset from Hugging Face's ``dataset`` (`link <https://huggingface.co/datasets>`_)
-- **partitioning datasets** - choose one of the implemented partitioning scheme or create your own.
-- **creating centralized datasets** - leave parts of the dataset unpartitioned (e.g. for centralized evaluation)
-- **visualization of the partitioned datasets** - visualize the label distribution of the partitioned dataset (and compare the results on different parameters of the same partitioning schemes, different datasets, different partitioning schemes, or any mix of them)
+- **Downloading datasets** - choose the dataset from Hugging Face's ``dataset`` (`link <https://huggingface.co/datasets>`_)(*)
+- **Partitioning datasets** - choose one of the implemented partitioning scheme or create your own.
+- **Creating centralized datasets** - leave parts of the dataset unpartitioned (e.g. for centralized evaluation)
+- **Visualization of the partitioned datasets** - visualize the label distribution of the partitioned dataset (and compare the results on different parameters of the same partitioning schemes, different datasets, different partitioning schemes, or any mix of them)
+
+.. note::
+
+  (*) Once the dataset is available on HuggingFace Hub it can be **immediately** used in ``Flower Datasets`` (no approval from the Flower team needed, no custom code needed).
 
 
 .. image:: ./_static/readme/comparison_of_partitioning_schemes.png