* update lr_updater.py file path
replace out-of-date links with master branch link
* Update code reference to newest version
1. fix typo err of `CosineAnnealingLrUpdaterHook`
2. update code ref links to the newest version (including `CosineAnnealingLrUpdaterHook`, `CyclicLrUpdaterHook`, `CyclicMomentumUpdaterHook`).
* [Refactor] change imgs_per_gpu to samples_per_gpu in config files
* [Docs] change imgs_per_gpu to samples_per_gpu in docs
* [Refactor] change imgs_per_gpu to samples_per_gpu in codes and add warnings
* [Fix] fix isort
* [Docs] fix docs format
* [Refactor] add related UT codes
* [Fix] fix isort
* fix links of docs
* [Docs]: Use shared menu from theme instead
* [Refactor]: Refactor the directory structure of docs
* [Fix]: Fix lint
* [Fix]: Fix __version__.py file link bug
Co-authored-by: fangyixiao18 <fangyx18@hotmail.com>