doc: Change the qrcode image to repo's url qrcode

Author: OUDON

README.md

@@ -1,5 +1,6 @@
 # An rMQR Code Generator
-![Lorem_ipsum](https://user-images.githubusercontent.com/14174940/171996095-4707be09-506e-4ef2-ab90-9942d6efc2ed.png)
+![reop-url](https://user-images.githubusercontent.com/14174940/172978619-accbf9d0-9dd8-4b19-b47e-ad139a68dcc9.png)
+
 
 This is an rMQR Code image generator implemented in Python. This is implemented based on [ISO/IEC 23941:2022](https://www.iso.org/standard/77404.html).