Fix Maven badge URL

Author: kelson42

README.md

@@ -1,5 +1,5 @@
 # Libkiwix binding for Java/Kotlin
 
-![Maven Central](https://img.shields.io/maven-central/v/org.kiwix.kiwixlib/kiwixlib)
+[![Maven Central](https://img.shields.io/maven-central/v/org.kiwix.kiwixlib/kiwixlib)](https://search.maven.org/artifact/org.kiwix.kiwixlib/kiwixlib)
 [![CodeFactor](https://www.codefactor.io/repository/github/kiwix/java-libkiwix/badge)](https://www.codefactor.io/repository/github/kiwix/java-libkiwix)
 [![License: GPL v3](https://img.shields.io/badge/License-GPLv3-blue.svg)](https://www.gnu.org/licenses/gpl-3.0)