Agregar soporte para deploy con docker

[PatrickGardiner]

1. Armar Dockerfile

   # Use an official Node.js runtime as the base image
   FROM node:20-alpine as node_build
   
   # Set the working directory inside the container
   WORKDIR /usr/src/app
   
   # Copy package.json and package-lock.json to the working directory
   COPY package*.json ./
   
   # Install app dependencies
   RUN npm install
   
   # Copy the rest of the application code to the working directory
   COPY . .
   
   # Expose the port that the app will run on
   EXPOSE 7070
   
   # Define the command to run your app
   CMD [ "npm", "start" ]

2. Agregar ayuda de build y run en el README.md

   ## Instanciar localmente
   
   ## NPM
   
   * Correr
       ```shell
       npm install
       npm start
       ```
   * Acceder:  `http://localhost:7070/api`
   
   ### Docker
   
   * Correr
       ```shell
       docker build -t api-dolar-argentina .
       docker run -p 80:7070 -d api-dolar-argentina
       ```
   
   * Acceder:  `http://localhost/api`