Add DETR readme.md (open-mmlab#4206)

* Add DETR readme.md

* update model zoo

* fix typo

Author: ZwwWayne

README.md

@@ -104,6 +104,7 @@ Supported methods:
 - [x] [YOLACT](configs/yolact/README.md)
 - [x] [CentripetalNet](configs/centripetalnet/README.md)
 - [x] [VFNet](configs/vfnet/README.md)
+- [x] [DETR](configs/detr/README.md)
 
 Some other methods are also supported in [projects using MMDetection](./docs/projects.md).
 

configs/detr/README.md

@@ -0,0 +1,25 @@
+# DETR
+
+## Introduction
+
+We provide the config files for DETR: [End-to-End Object Detection with Transformers](https://arxiv.org/abs/2005.12872).
+
+```BibTeX
+@inproceedings{detr,
+  author    = {Nicolas Carion and
+               Francisco Massa and
+               Gabriel Synnaeve and
+               Nicolas Usunier and
+               Alexander Kirillov and
+               Sergey Zagoruyko},
+  title     = {End-to-End Object Detection with Transformers},
+  booktitle = {ECCV},
+  year      = {2020}
+}
+```
+
+## Results and Models
+
+| Backbone | Model | Lr schd | Mem (GB) | Inf time (fps) | box AP | Config | Download |
+|:------:|:--------:|:-------:|:--------:|:--------------:|:------:|:------:|:--------:|
+| R-50 | DETR  |150e ||  | | [config](https://github.com/open-mmlab/mmdetection/tree/master/configs/detr/detr_r50_8x4_150e_coco.py) | [model]() | [log]() |

docs/model_zoo.md

@@ -162,6 +162,9 @@ Please refer to [CentripetalNet](https://github.com/open-mmlab/mmdetection/blob/
 ### ResNeSt
 Please refer to [ResNeSt](https://github.com/open-mmlab/mmdetection/blob/master/configs/resnest) for details.
 
+### DETR
+Please refer to [DETR](https://github.com/open-mmlab/mmdetection/blob/master/configs/detr) for details.
+
 ### Other datasets
 
 We also benchmark some methods on [PASCAL VOC](https://github.com/open-mmlab/mmdetection/blob/master/configs/pascal_voc), [Cityscapes](https://github.com/open-mmlab/mmdetection/blob/master/configs/cityscapes) and [WIDER FACE](https://github.com/open-mmlab/mmdetection/blob/master/configs/wider_face).