* add ZeroOptimizer to optim

* resolve `duplicate label` warnings

* upgrade docutils && shpinx to resolve `unknown directive or role` warnings

* fix typo

* resolve literal_block && heading warnings

* resolve json literal_block warnings

* resolve python literal_block warnings

* resolve bunches of reference warnings

* resolve bunches of docstring warnings

* resolve warnings in autosummary

* resolve remaining warnings in en docs

* resolve heading warnings in zh_cn docs

* resolve remaining warnings in zh_cn docs

* fix as comments

* fix as comments

* [Docs] Fix failed link in registry

* fix typo

* [Docs] Translate data transform tutorial and migration docs.

* Update according to comments

* Update image link

* [WIP] Refactor-docs-structure

* [Docs] Check link and fix rst  (#498)

* check link

* fix rst

* Fix conf.py

* Fix lint

* minor refine

* minor refine

* modify zh_readme and index.rst

* add migration exampls get_started design to en

* add tutorials to en

* correct chinese doc link

* Apply suggestions from code review

* Update docs/en/advanced_tutorials/distributed.md

Co-authored-by: Zaida Zhou <58739961+zhouzaida@users.noreply.github.com>

Co-authored-by: Mashiro <57566630+HAOCHENYE@users.noreply.github.com>

* [Docs] Make API of docs clearer

* minor fix

* fix md format

* Add pyupgrade pre-commit hook

* fix ut

* remove comments

* [Docs] Configure the documentation

* delete mypy.ini