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

@@ -37,7 +37,7 @@ paperswithcode_id: cord-19
 pretty_name: CORD-19
 ---
 
-# Dataset Card Creation Guide
+# Dataset Card for CORD-19
 
 ## Table of Contents
 - [Dataset Description](#dataset-description)
@@ -147,14 +147,13 @@ Extra fields based on selected configuration during loading:
 
 No annotation provided in this dataset so all instances are provided in training split.
 
-The sizes of each configurations are:
-
-|          | Tain   |
-| -----    | ------ |
-| metadata | 368618  |
-| fulltext | 368618  |
-| embeddings | 368618  |
+The sizes of each configuration are:
 
+|            |  train |
+|------------|-------:|
+| metadata   | 368618 |
+| fulltext   | 368618 |
+| embeddings | 368618 |
 
 ## Dataset Creation