Fix typo in train split name (#3751)

* Fix typo in README guide

* Fix split naming and table alignment in README guide

* Fix split naming and table alignment in all datasets

* Fix previously malformed dataset cards

* Fix previously malformed dataset cards

Commit from https://github.com/huggingface/datasets/commit/af6e54febe3b822118dfed28ddb797d8350e5d27

README.md

@@ -104,9 +104,9 @@ the dataset distribution and balance for each class looks like the following
 
 The dataset is not split. 
 
-|           | Tain   | 
-|---------- | ------ | 
-|no split   | 10,065  | 
+|          |   train |
+|----------|--------:|
+| no split |  10,065 |
 
 ## Dataset Creation