Update README.md (#33)

Author: leolost2605

README.md

@@ -5,4 +5,4 @@ Keep track of your grades
 <br>
 
 <p align="center"><img alt="The main view page of Gradebook" src="https://raw.githubusercontent.com/leolost2605/Gradebook/main/data/screenshot-main.png"/></p>
-<p align="center"><a href='https://flathub.org/apps/io.githib.leolost2605.gradebook'><img width='260' alt='Download Gradebook on Flathub' src='https://dl.flathub.org/assets/badges/flathub-badge-en.png'/></a></p>
+<p align="center"><a href='https://flathub.org/apps/io.github.leolost2605.gradebook'><img width='260' alt='Download Gradebook on Flathub' src='https://dl.flathub.org/assets/badges/flathub-badge-en.png'/></a></p>