Merge pull request d2l-ai#803 from d2l-ai/master

v2.0.0-alpha1 release

Merge pull request d2l-ai#686 from d2l-ai/master

v2.0.0-alpha0

[1.0.0] release

add back build env

rnn and backprop fix

Merge pull request d2l-ai#213 from astonzhang/nin

consistent indentation

Update index.md

fix latex bug

update data_iter (d2l-ai#87)

Fix typo (d2l-ai#66)