update readme

files/image_refresh/Dockerfile

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+# Use an official Node runtime as a parent image
+FROM node:14
+
+# Create and change to the app directory
+WORKDIR /usr/src/app
+
+# Copy package.json and package-lock.json
+COPY package*.json ./
+
+# Install any needed packages specified in package.json
+RUN npm install
+
+# Bundle app source inside Docker container
+COPY . .
+
+# Make port 3000 available to the world outside this container
+EXPOSE 3000
+
+# Define environment variable
+ENV NAME World
+
+# Run app.py when the container launches
+CMD ["node", "server.js"]