feature : add docker image size

Author: beachdweller

README.md

@@ -1,6 +1,7 @@
 [![Build Status](https://github.com/kangwonlee/gemini-python-tutor/workflows/build/badge.svg)](https://github.com/kangwonlee/gemini-python-tutor/actions)
 [![GitHub release](https://img.shields.io/github/release/kangwonlee/gemini-python-tutor.svg)](https://github.com/kangwonlee/gemini-python-tutor/releases)
 [![Docker Image Version (latest by date)](https://img.shields.io/docker/v/beachgoer/gemini-python-tutor?label=Docker%20Hub&logo=docker)](https://hub.docker.com/r/beachgoer/gemini-python-tutor)
+[![Docker Image Size (latest by date)](https://img.shields.io/docker/image-size/beachgoer/gemini-python-tutor?logo=docker)](https://hub.docker.com/r/beachgoer/gemini-python-tutor)
 
 # AI Python Code Tutor (Gemini)