Add Elastic Stack logo to ELK badge

README.md

 # Elastic stack (ELK) on Docker
 
-[![Join the chat at https://gitter.im/deviantony/docker-elk](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/deviantony/docker-elk?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
-[![Elastic Stack version](https://img.shields.io/badge/ELK-7.9.2-blue.svg?style=flat)](https://github.com/deviantony/docker-elk/issues/539)
+[![Elastic Stack version](https://img.shields.io/badge/Elastic%20Stack-7.9.2-00bfb3?style=flat&logo=elastic-stack)](https://github.com/deviantony/docker-elk/issues/539)
 [![Build Status](https://github.com/deviantony/docker-elk/workflows/CI/badge.svg?branch=master)](https://github.com/deviantony/docker-elk/actions?query=workflow%3ACI+branch%3Amaster)
+[![Join the chat at https://gitter.im/deviantony/docker-elk](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/deviantony/docker-elk?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 
 Run the latest version of the [Elastic stack][elk-stack] with Docker and Docker Compose.