Include section to show expectations of a successful build of the project via docker

Explain the changes

Before the forem_rails container finishes its job, I keep seeing the following console logs

forem_sidekiq | 2021/10/04 11:45:43 Problem with dial: dial tcp 172.20.0.6:3000: connect: connection refused. Sleeping 20s
forem_seed | 2021/10/04 11:45:43 Problem with dial: dial tcp 172.20.0.6:3000: connect: connection refused. Sleeping 20s

These logs confused me a lot and made me think that I did something wrong. I saw this happening for a whole 15mins while the other containers such as forem_rails and forem_webpack are doing their job. These logs only stopped after forem_rails was done.

Later on, I also keep seeing repetitive logs of

forem_sidekiq | 2021-10-04T11:58:53.179Z pid=17 tid=5sbd class=PodcastEpisodes::CreateWorker jid=a62b46c37f05a191b0378648 INFO: start
forem_sidekiq | 2021-10-04T11:58:53.989Z pid=17 tid=1qq9 class=PodcastEpisodes::CreateWorker jid=83c1b062229b7a3c8e3beb95 elapsed=2.291 INFO: done

which had no indications of when or where the process will end. (Up till here, it already took 30-40mins)

Suggested changes

1. Include some successful console logs for different containers will help demystify the build process through Docker.
2. A notice to tell them there will be certain logs that would be repetitive and not a cause of concern, to help ease minds that are waiting

Additional context

I'm not familiar to Docker, but perhaps a better way to resolve this problem is to set the logs on the 2 docker containers forem_sidekiq & forem_seed to be quiet until the other containers are done with their scripts.

Review the Docker startup output for forem_rails, forem_webpack, forem_sidekiq, and forem_seed to identify representative successful logs and the expected completion point. Update the relevant project documentation with those examples and explain that the connection-refused and repetitive worker logs can occur during startup. Done means a new Docker user can recognize a successful build and understand when the process has finished.