Add Wiki Lingua Dataset
I am done adding the dataset. Requesting to review and advise. looks like this PR has changes about many other files than the ones for WIki Lingua 

Can you create another branch and another PR please ? Any reason to have english as the default config over the other languages ? > looks like this PR has changes about many other files than the ones for WIki Lingua
> 
> Can you create another branch and another PR please ?

Ok, I will create another branch and submit a fresh PR. > Any reason to have english as the default config over the other languages ?

The data for all other languages has a direct reference to English article. Thus, I kept English as default. closing in favor of #1470 
Hello,

This is my first PR. 

I have added Wiki Lingua Dataset along with dataset card to the best of my knowledge.
There was one hiccup though. I was unable to create dummy data because the data is in pkl format.
From the document, I see that:
```At the moment it supports data files in the following format: txt, csv, tsv, jsonl, json, xml```

