docs: adding docker image shields (#37)

Author: Frnd-me

README.md

@@ -5,7 +5,7 @@
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-[![License: GPL v3](https://img.shields.io/badge/License-GPLv3-blue.svg)](LICENSE.md) [![Build](https://github.com/UIBK-DPS-DC/Cirrina/actions/workflows/build.yml/badge.svg?event=push)](https://github.com/UIBK-DPS-DC/Cirrina/actions/workflows/build.yml?event=push)
+[![License: GPL v3](https://img.shields.io/badge/License-GPLv3-blue.svg)](LICENSE.md) [![Build](https://github.com/UIBK-DPS-DC/Cirrina/actions/workflows/build.yml/badge.svg?event=push)](https://github.com/UIBK-DPS-DC/Cirrina/actions/workflows/build.yml?event=push) ![Docker Image Version (tag)](https://img.shields.io/docker/v/marlonetheredgeuibk/cirrina/unstable?color=red) ![Docker Image Version (tag)](https://img.shields.io/docker/v/marlonetheredgeuibk/cirrina/stable?color=blue)
 
 Cirrina, a distributed Collaborative State Machines (CSM) runtime for the Cloud-Edge-IoT continuum. Collaborative state machines is a state
 machine-based programming model for the Cloud-Edge-IoT continuum. For more information, please visit the