Remove a copy-paste sentence in dataset cards (#4281)

Commit from https://github.com/huggingface/datasets/commit/bf6108b8e09fae44787a6a7b20b8718c6e86dd7f

README.md

@@ -61,8 +61,6 @@ Both "arxiv" and "pubmed" have two features:
 
 ## Dataset Structure
 
-We show detailed information for up to 5 configurations of the dataset.
-
 ### Data Instances
 
 #### arxiv