* Update INSTALL_cn.md

* Update INSTALL.md

Add  chapter "Use built Docker images".

* update link for release/2.4. test=document_fix

Reorder installation steps for paddledet in docs/tutorials/INSTALL.md

* fix link

* fix_install_docs

* fix_install_docs2

* update install docs

* fix slim doc,test=document_fix

* update 2.0.1

* update doc on develop, test=document_fix

* update dependency of ppdet and paddle, test=document_fix

* update docs, test=document_fix

* remove rbox-iou-ops dependence

* update install doc

* Update install doc and deploy doc.

* update v0.5 release note

* update some comments

* fix voc dataset and docs

* add custom datsset demo

* optimize python path

* Remove `pycocotools` from `requirements.txt`

git version is required for numpy > 1.18

* Remove `cython`, add pip install doc

* fix all documentation

* fix docs conf.py

* fix some error

* fix readthedocs

* move path to PaddleDetection repo in docs

* refine README

* update code & doc

* change voc_loader

* Update PaddleDetection README
* Fix some link

* refine download sh to py

* update QUICK_STARTED

Add PaddleDetection docs & some model configs

* add cn doc for INSTALL/GETTING_START

* cn for GETTING_STARTED

* fix doc

* Fix some docs
* Unify COCO and VOC
* Change PASCAL to Pascal
* Unify dataset/coco

* improve quality of images

* update url for install doc

* Rename object_detection to PaddleDetection
* Small fix for doc