* add doc

* add FAQ

* update link develop -> release/2.1. test=document_fix

* update 2.1 readme

* update en doc, test=document_fix

* update doc, test=document_fix
Co-authored-by: NGuanghua Yu <742925032@qq.com>

* fix jde negative coords

* update jde model zoo

* describe format for some txt, test=document_fix

* fix mot doc

* remove image_lists, fix all mot docs, add custom data

* fix doc, test=document_fix

* fix dov

* fix doc format, test=document_fix

* update install docs

* fix slim doc,test=document_fix

* add config for jde and deepsort, add engine metric tools

* add mot_metrics

* fix configs engine and others

* fix configs others

* move configs

* fix ap_per_class, fix doc

* fix test_mode, seqs

* fix test_mode to metric

* fix JDE arch metric

* clean requirement

* add to requirement

* add inference benchmark

* add mot data

* fix operators, source

* fix data source transform

* fix parse_dataset register_op

* fix scale_factor, RandomAffine

* add assert for check

* fix ci

* add lite demo

* 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

* fix some docs error

* move ssld model, test=document_fix

* fix typo, test=document_fix

* add 2.0 CHANGLOG

* update README

* update doc, test=document_fix

* add citation

* update citation and ppyolo doc

* Add S2ANet model for Oriented Object Detection.

* add docs for custom dataset, reader and model technical

* modify docs according to review, test=document_fix

* modify READER.md, test=document_fix

* add config annotation doc, test=document_fix

* update doc of config

* mlp_dim-->out_channel of TwoFCHead

* update doc, test=document_fix

* update doc, test=document_fix

* update quick_start

* update get_started

* update doc, test=document_fix