Update README.md (#3778)

README.md

@@ -53,7 +53,7 @@ ncnn 是一个为手机端极致优化的高性能神经网络前向计算框架
 * Face Detection: [MTCNN](https://github.com/ipazc/mtcnn) [RetinaFace](https://github.com/biubug6/Pytorch_Retinaface) [scrfd](https://github.com/nihui/ncnn-android-scrfd) ...
 * Detection: [VGG-SSD](https://github.com/lzx1413/CAFFE_SSD) [MobileNet-SSD](https://github.com/chuanqi305/MobileNet-SSD) [SqueezeNet-SSD](https://github.com/chuanqi305/SqueezeNet-SSD) [MobileNetV2-SSDLite](https://github.com/chuanqi305/MobileNetv2-SSDLite) [MobileNetV3-SSDLite](https://github.com/XiaoyuHuang96/MobilenetV3SSDLite-tfkeras) ...
 * Detection: [Faster-RCNN](https://github.com/rbgirshick/py-faster-rcnn) [R-FCN](https://github.com/daijifeng001/R-FCN) ...
-* Detection: [YOLOV2](https://github.com/longcw/yolo2-pytorch) [YOLOV3](https://github.com/ultralytics/yolov3) [MobileNet-YOLOV3](https://github.com/eric612/MobileNet-YOLO) [YOLOV4](https://github.com/Tianxiaomo/pytorch-YOLOv4) [YOLOV5](https://github.com/ultralytics/yolov5) [YOLOX](https://github.com/Megvii-BaseDetection/YOLOX) ...
+* Detection: [YOLOv2](https://github.com/longcw/yolo2-pytorch) [YOLOv3](https://github.com/ultralytics/yolov3) [MobileNet-YOLOv3](https://github.com/eric612/MobileNet-YOLO) [YOLOv4](https://github.com/Tianxiaomo/pytorch-YOLOv4) [YOLOv5](https://github.com/ultralytics/yolov5) [YOLOX](https://github.com/Megvii-BaseDetection/YOLOX) ...
 * Detection: [NanoDet](https://github.com/RangiLyu/nanodet)
 * Segmentation: [FCN](https://github.com/unsky/FPN) [PSPNet](https://github.com/hszhao/PSPNet) [UNet](https://github.com/zhixuhao/unet) [YOLACT](https://github.com/dbolya/yolact) ...
 * Pose Estimation: [SimplePose](https://github.com/dog-qiuqiu/Ultralight-SimplePose) ...