Explain the use of the `COPY` command in the NodeJS example (#13711)
Explain the use of the `COPY` command in the NodeJS example (#13711)

* Explain the use of the COPY command in nodejs example

* Format updates

Co-authored-by: Usha Mandya <63fc8324d194bb900191b7ad7215ea10fd135fb2@users.noreply.github.com>
docker/docker.github.io,thaJeztah/docker.github.io,thaJeztah/docker.github.io,docker/docker.github.io,thaJeztah/docker.github.io,thaJeztah/docker.github.io,docker/docker.github.io,docker/docker.github.io,thaJeztah/docker.github.io,docker/docker.github.io