typo: yusing --> using

Author: CC11001100

README.md

@@ -436,7 +436,7 @@ To get started, simply fork this repo. Please refer to [CONTRIBUTING.md](CONTRIB
 
 - [Build A Document Scanner](https://www.pyimagesearch.com/2014/09/01/build-kick-ass-mobile-document-scanner-just-5-minutes/)
 - [Build A Face Detector using OpenCV and Deep Learning](https://www.pyimagesearch.com/2018/02/26/face-detection-with-opencv-and-deep-learning/)
-- [Build fastest custom object Detection system yusing YOLOv3(video playlist)](https://www.youtube.com/playlist?list=PLKHYJbyeQ1a0oGzgRXy-QwAN1tSV4XZxg)
+- [Build fastest custom object Detection system using YOLOv3(video playlist)](https://www.youtube.com/playlist?list=PLKHYJbyeQ1a0oGzgRXy-QwAN1tSV4XZxg)
 - [Build a Face Recognition System using OpenCV, Python and Deep Learning](https://www.pyimagesearch.com/2018/06/18/face-recognition-with-opencv-python-and-deep-learning/)
 - [Detect The Salient Features in an Image](https://www.pyimagesearch.com/2018/07/16/opencv-saliency-detection/)
 - [Build A Barcode Scanner](https://www.pyimagesearch.com/2018/05/21/an-opencv-barcode-and-qr-code-scanner-with-zbar/)