Onboard new Mailchimp account users

[calvin-lau-sig7]

What

Onboard and train more team members on how to use Mailchimp email tool.

Should be supported by documentation written in #2393 and answer any questions.

Why

We now have 5 user accounts, so onboarding more team members will let us send emails more efficiently.
This would also set up the Prototype team to start and manage their own mailing list.

Who needs to work on this

Content designers, Technical writer, Community designer

Who needs to review this

New account users, possibility delivery manager

Done when

• Account invites sent and accepted
• Documentation sent
• Do a walkthrough of docs or answer questions asynchronously
• Demonstration of sending an email (perhaps for 4.4.0?)