Convert dataset sizes from base 2 to base 10 in the dataset card

Convert dataset sizes from base 2 (MiB) to base 10 (MB) in the dataset card, as it is the case in the dataset viewer.
See: https://github.com/huggingface/datasets/issues/5708

README.md

@@ -206,9 +206,9 @@ correction on the test set for example, is:
 
 #### conllpp
 
-- **Size of downloaded dataset files:** 4.63 MB
-- **Size of the generated dataset:** 9.78 MB
-- **Total amount of disk used:** 14.41 MB
+- **Size of downloaded dataset files:** 4.85 MB
+- **Size of the generated dataset:** 10.26 MB
+- **Total amount of disk used:** 15.11 MB
 
 An example of 'train' looks as follows.
 ```