* 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 model save load guide

* polish details

* fix index number

* polish hapi & add note

* 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