clarify start up instructions for those completely new to docker

[dcconner]

Added a bit more step-by-step instructions on docker start up based on question from tester on new computer.

For docker compose run base bash is the bash necessary?

I've only done docker compose run base in new terminals and it seemed to work fine.

[sea-bass]

Thank you!

To answer your question, I think the bash is not needed since I restored the entrypoint in #66 -- but, see my inline comment for what it should be!

[sea-bass]

I didn't notice this before, but doing docker compose run base, this actually creates a new container instead of attaching to the one that was just started.

So we actually want to do this to attach to the existing container.

docker compose exec base bash

You can verify the difference by typing docker ps.

[dcconner]

@ct2034 if you approve, feel free to squash and merge

[dcconner]

Modified p3 world to match description. I have NOT tested this with other technologies to make sure it did not break their demonstrations. Either we need this change, or change the description in README to be consistent

[sea-bass]

I'd say just merge this PR, but maybe explicitly send an email about the modified world file since everyone will need to tweak the solutions.