Update README.md

Author: justserpapi

README.md

@@ -6,7 +6,7 @@
 
 [![Maven Central](https://img.shields.io/maven-central/v/com.justserpapi/justserpapi-java)](https://central.sonatype.com/artifact/com.justserpapi/justserpapi-java)
 [![Java](https://img.shields.io/badge/java-11%2B-2f81f7)](https://www.oracle.com/java/technologies/downloads/)
-[![Docs](https://img.shields.io/badge/docs-justserpapi.com-32c955)](https://justserpapi.com/)
+[![Docs](https://img.shields.io/badge/docs-justserpapi.com-32c955)](https://docs.justserpapi.com/?utm_source=github&utm_medium=referral&utm_campaign=justserpapi_justserpapi_java&utm_content=repo_readme)
 [![License](https://img.shields.io/badge/license-Apache%202.0-f28c28)](LICENSE)
 
 Official Java SDK for [JustSerpAPI](https://justserpapi.com/).