update installation

Author: prepkg

README.md

@@ -38,14 +38,18 @@ Tested on Raspberry Pi 4 Model B (8 GB).
 wget https://github.com/prepkg/opencv-raspberrypi/releases/latest/download/opencv.deb
 ```
 
+```shell
+sudo apt install -y ./opencv.deb
+```
+
 * 64-bit:
 
 ```shell
 wget https://github.com/prepkg/opencv-raspberrypi/releases/latest/download/opencv_64.deb
 ```
 
 ```shell
-sudo apt install -y ./opencv.deb
+sudo apt install -y ./opencv_64.deb
 ```
 
 ## Uninstall