update docker-compose.yml for medium article with both api and database

docker-compose.yml

version: "3.7"
services:
  api:
    build:
      context: .
      dockerfile: web.Dockerfile
    image: api
    networks:
      - todonet
    depends_on: 
      - "db"
    env_file: 
      - .env
    ports:
      - "9080:8080"
    container_name: apii
  db:
    image: mysql:5
    env_file:
      - .env
    networks:
      - todonet
    ports:
      - "3306:3306"
    # we can prepopulate database with .sql file by uncommenting volumes
    # volumes:
    #   - ./initial.sql:/docker-entrypoint-initdb.d/init.sql
    container_name: todo_db
networks:
  todonet: