Remove redundant PointRCNN README.md (#1125)

configs/pointrcnn/README.md

-# PointRCNN: 3D Object Proposal Generation and Detection from Point Cloud
-
-## Introduction
-
-<!-- [ALGORITHM] -->
-
-We implement PointRCNN and provide its results with checkpoints on KITTI dataset.
-
-```
-@InProceedings{Shi_2019_CVPR,
-    author = {Shi, Shaoshuai and Wang, Xiaogang and Li, Hongsheng},
-    title = {PointRCNN: 3D Object Proposal Generation and Detection From Point Cloud},
-    booktitle = {The IEEE Conference on Computer Vision and Pattern Recognition (CVPR)},
-    month = {June},
-    year = {2019}
-}
-```
-
-## Results
-
-### KITTI
-
-|  Backbone   |Class| Lr schd | Mem (GB) | Inf time (fps) | mAP | Download |
-| :---------: | :-----: |:-----: | :------: | :------------: | :----: |:----: |
-|    [PointNet++](./pointrcnn_2x8_kitti-3d-3classes.py) |3 Class|cyclic 80e|7.1||70.39||