Add bibtex for new paper

[sshleifer]

and link

[codecov]

Codecov Report

Merging #6656 into master will increase coverage by 1.26%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #6656      +/-   ##
==========================================
+ Coverage   79.01%   80.27%   +1.26%     
==========================================
  Files         156      156              
  Lines       28248    28248              
==========================================
+ Hits        22320    22677     +357     
+ Misses       5928     5571     -357     

Impacted Files	Coverage Δ
src/transformers/modeling_tf_roberta.py	45.41% <0.00%> (-47.81%)	⬇️
src/transformers/modeling_t5.py	77.63% <0.00%> (-6.21%)	⬇️
src/transformers/modeling_utils.py	87.50% <0.00%> (-0.56%)	⬇️
src/transformers/modeling_tf_utils.py	86.97% <0.00%> (+1.62%)	⬆️
src/transformers/modeling_roberta.py	97.08% <0.00%> (+19.70%)	⬆️
src/transformers/modeling_tf_xlnet.py	92.17% <0.00%> (+71.04%)	⬆️

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[sgugger]

Just checking, there is no anonymity period, right?

[sshleifer]

no sasha tweeted it https://twitter.com/srush_nlp/status/1283433427212079104?s=20