Added some papers and articles

[just1900]

First, thanks to this repo and those who have contributed to this repo! I added some papers and articles about transformer-based music generation and RL(reinforcement Learning) methods using in music research.

[ybayle]

Hi @LegendJ Thank you for your contribution!

I've fixed some part of your contribution and generated again the images and details depending on your changes, could you check that everything was updated properly in the main repo on the master branch?

Additionnaly, I've updated CONTRIBUTING.md with details to check when you fill in bib fields. In order to maintain some coherence it would be better for your next contribution to:

• Make sure the title is not in all caps
• Check that all authors in the pdf files are present in the bib author field
• mark arxiv article as @unpublished. If you know of a possible submission use note = {Submitted to "NameOfJournalOrConference"}
• Fill in all the fields suggested and if there are not applicable or if the article does not detail this field, insert "fieldName = {No}"