how to make heroku yml code example

Example: heroku.yml

setup:
  addons:
    - plan: heroku-postgresql
      as: DATABASE
  config:
    S3_BUCKET: my-example-bucket
build:
  docker:
    web: Dockerfile
    worker: worker/Dockerfile
  config:
    RAILS_ENV: development
    FOO: bar
release:
  command:
    - ./deployment-tasks.sh
  image: worker
run:
  web: bundle exec puma -C config/puma.rb
  worker: python myworker.py
  asset-syncer:
    command:
      - python asset-syncer.py
    image: worker