update readme (#7867)

Author: chhluo

README.md

@@ -143,6 +143,7 @@ Results and models are available in the [model zoo](docs/en/model_zoo.md).
             <li><a href="configs/yolox">YOLOX (CVPR'2021)</a></li>
             <li><a href="configs/deformable_detr">Deformable DETR (ICLR'2021)</a></li>
             <li><a href="configs/tood">TOOD (ICCV'2021)</a></li>
+            <li><a href="configs/centripetalnet">CentripetalNet (CVPR'2020)</a></li>
       </ul>
       </td>
       <td>

README_zh-CN.md

@@ -142,6 +142,7 @@ MMDetection 是一个基于 PyTorch 的目标检测开源工具箱。它是 [Ope
             <li><a href="configs/yolox">YOLOX (CVPR'2021)</a></li>
             <li><a href="configs/deformable_detr">Deformable DETR (ICLR'2021)</a></li>
             <li><a href="configs/tood">TOOD (ICCV'2021)</a></li>
+            <li><a href="configs/centripetalnet">CentripetalNet (CVPR'2020)</a></li>
       </ul>
       </td>
       <td>