README: Add Maven Central badge (#32)

* Initial plan

* Add Maven Central badge to README

Co-authored-by: patrickmichalik <[email protected]>

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Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: patrickmichalik <[email protected]>

Author: Copilot

README.md

@@ -2,6 +2,7 @@
 
 [![Kotlin](https://img.shields.io/badge/Kotlin-2.2.20-blue.svg)](https://kotlinlang.org)
 [![License](https://img.shields.io/badge/License-MIT-green.svg)](./LICENSE)
+[![Maven Central](https://img.shields.io/maven-central/v/com.swmansion.kmpmaps/kmp-maps)](https://central.sonatype.com/artifact/com.swmansion.kmpmaps/kmp-maps)
 
 `kmp-maps` provides a unified map component for Compose Multiplatform applications, offering seamless integration with native map APIs on both Android and iOS platforms.