Write a guide on environment setup, troubleshooting, and preparations (e.g. downloads)

[joyeecheung]

We should collect these information in a central place (maybe a document in this repo) and send it out to participants before the event.

Also a FAQ covering things like

• I am seeing some unrelated test failures, is that OK?
• What does it mean to replace fixturesDir with fixtures?
• Which branch should I target?
• Reviewers asked me to rebase, what does it mean?
• etc.

would be very useful.

[joyeecheung]

FTR I am writing one (and trying to do a screencast on the build & test & git stuff), but I've got my hands pretty full right now so probably won't finish them anytime soon. Anyone willing to do it can take it now.

[Trott]

Ping @nodejs/collaborators: If anyone wants to write something like this up and put it somewhere linkable that would be great. Speaking just for me, a pull request adding a page like this to https://github.com/Trott/nodetodo would be super-duper welcome.

[gibfahn]

Related: Trott/nodetodo#4

[bzoz]

I've created a Boxstarter script for Windows boxes. PR to include it in Node: nodejs/node#17046