Add info about tool/language versions?

[c-anothus]

I just ran through installing nvm, node v16.10, yarn v1.22.18 (latest), and docker-compose v1.25.0. I wasn't quite sure which versions to install or how much it mattered for this tooling set. I noticed that yarn[1] and docker-compose[2] both have a v2 out and documentation on how to migrate.

I found the current node and yarn versions on CircleCI, and figured that we wanted legacy docker-compose since that was what the command syntax matched.

If it matters, specifying version would be good. If it doesn't matter, mentioning that would also be useful.

[1] https://yarnpkg.com/getting-started/migration#why-should-you-migrate
[2] https://docs.docker.com/compose/cli-command/#compose-switch - v2 not GA on linux yet