add: ICLR2021 data

[matsutakk]

I executed your notebook and made iclr2021.json. Also, I added a new line to *.html file to include ICLR 2021 and changed the default conference year in js/index.js.

[matsutakk]

If I include comments in papers, the data.json became over 100MB. So, I did not include them.

[matsutakk]

p.s. thank you for absolutely great site!