Added `pn_summary` dataset
As always, I got stuck in the correct order of imports 😅
@lhoestq, It's finished! @lhoestq, It's done! Is there anything else that needs changes?
#1635 

You did a great job with the fluent procedure regarding adding a dataset. I took the chance to add the dataset on my own. Thank you for your awesome job, and I hope this dataset found the researchers happy, specifically those interested in Persian Language (Farsi)!