* fix some docs

* fix links

* fix sample code

* upgrade guide added

* update migration tool page

* minor change

* minor change

* update codes and format

* no ci for upgrade_guide

* minor

* minor

* fix___init_bug

* fix migration guide

* add api_reference test=develop

* fix style test=develop

* change faq to chinese test=develop

* add release note en

* fix release note test=develop

* fix api_reference test=develop

* fix style test=develop

* add migration test=develop

* fix_logs test=develop

* fix_migration_guide and add dygraph to static test=develop

* fix_install test=develop

* fix install and args

* fix_style test=develop

* fix docs test=develop

* add_guides for paddle test=develop

* add_guides to index test=develop

* fix_guides_index test=develop

* fix_en_docs test=develop

* remove old index test=develop