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

@@ -21,7 +21,7 @@ paperswithcode_id: gutenberg-poem-dataset
 pretty_name: Gutenberg Poem Dataset
 ---
 
-# Dataset Card Creation Guide
+# Dataset Card for Gutenberg Poem Dataset
 
 ## Table of Contents
 - [Dataset Description](#dataset-description)
@@ -90,9 +90,9 @@ Example of one instance in the dataset.
 
 The dataset is split into a `train`, `validation`, and `test` split with the following sizes:
 
-|                            | Tain   | Valid | Test  |
-| -----                      | ------ | ----- | ----- |
-| Number of examples         | 892    | 105   | 104   |
+|                    | train | validation | test |
+|--------------------|------:|-----------:|-----:|
+| Number of examples |   892 |        105 |  104 |