add documentation on download size and streaming

README.md

@@ -93,6 +93,10 @@ Our goal is to raise awareness for and advance Pan-African English ASR research,
 
 The `datasets` library allows you to load and pre-process your dataset in pure Python, at scale. The dataset can be downloaded and prepared in one call to your local drive by using the `load_dataset` function. 
 
+The entire dataset is ~120GB and may take about 2hrs to download. If you have disk space or bandwidth limitations, you can use `streaming` mode described below to work with smaller subsets of the data. 
+
+In future updates, you will be able to pass a config to the `load_dataset` function and download only a subset of the data corresponding to a specific accent of interest. The example provided below is `isizulu`.
+
 For example, to download the isizulu config, simply specify the corresponding language config name, list of supported accents provided in accent list section below:
 ```python
 from datasets import load_dataset