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

@@ -95,11 +95,12 @@ One example of the translation is as below:
 ### Data Splits
 
 The dataset is divided into two splits. All the headlines are scraped from news websites on the internet.
-|       | Tain   | Valid | Test  |
-| ----- | ------ | ----- | ----- |
-| ru-pl |  20001 | 3001  | 2969  |
-| pl-ru |  20001 | 3001  | 2969  |
-| en-pl | 129255 | 1000  | 9845  |
+
+|       |  train | validation | test |
+|-------|-------:|-----------:|-----:|
+| ru-pl |  20001 |       3001 | 2969 |
+| pl-ru |  20001 |       3001 | 2969 |
+| en-pl | 129255 |       1000 | 9845 |
 
 ## Dataset Creation
 
@@ -162,7 +163,17 @@ The organization details of PolEval is present in this [link](http://2019.poleva
 
 ### Citation Information
 
-[More Information Needed]
+```
+@proceedings{ogr:kob:19:poleval,
+  editor    = {Maciej Ogrodniczuk and Łukasz Kobyliński},
+  title     = {{Proceedings of the PolEval 2019 Workshop}},
+  year      = {2019},
+  address   = {Warsaw, Poland},
+  publisher = {Institute of Computer Science, Polish Academy of Sciences},
+  url       = {http://2019.poleval.pl/files/poleval2019.pdf},
+  isbn      = "978-83-63159-28-3"}
+}
+```
 
 ### Contributions