Update README.md

README.md

@@ -88,6 +88,20 @@ There is only one split, `train`, that contains 141,047,697 examples.
 
 `OBELISC` with images replaced by their URLs weighs 666.6 GB (unwanted!) in arrow format and 377 GB in this uploaded `parquet` format.
 
+## Configs
+
+The default config, downloaded when nothing is specified in the config argument, with
+```
+from datasets import load_dataset
+
+ds = load_dataset("HuggingFaceM4/OBELISC")
+```
+corresponds to the original version of the dataset.
+
+When building the dataset, we sent every image URL to the Spawning AI API and removed all the opted-out images.
+However, we noticed afterward that some images might not be opted-out, but the whole web page containing them is.
+This is why we created another config of the dataset to additionally filter out opted-out web pages, that can be loaded with `ds = load_dataset("HuggingFaceM4/OBELISC", config_name="opt_out_docs_removed")`.
+
 ### Visualization of OBELISC documents
 
 https://huggingface.co/spaces/HuggingFaceM4/obelisc_visualization