docs: Add SLOC counter to README

Author: SMadani

README.md

@@ -3,6 +3,7 @@
 [![Maven Release](https://maven-badges.herokuapp.com/maven-central/com.vonage/server-sdk-kotlin/badge.svg)](https://central.sonatype.com/artifact/com.vonage/server-sdk-kotlin)
 [![Build Status](https://github.com/Vonage/vonage-kotlin-sdk/actions/workflows/build.yml/badge.svg)](https://github.com/Vonage/vonage-kotlin-sdk/actions/workflows/build.yml)
 [![codecov](https://codecov.io/gh/Vonage/vonage-kotlin-sdk/graph/badge.svg?token=YNBJUD8OUT)](https://codecov.io/gh/Vonage/vonage-kotlin-sdk)
+![SLOC](https://sloc.xyz/github/vonage/vonage-kotlin-sdk/)
 [![Contributor Covenant](https://img.shields.io/badge/Contributor%20Covenant-v2.0%20adopted-ff69b4.svg)](CODE_OF_CONDUCT.md)
 [![License](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](LICENSE.txt)