Set up Mailchimp automated emails

Set up Mailchimp automated emails for new signs up through Meetup. Update Meetup Welcome message to add:

"1. Sign up for our email list: eepurl.com/gTNkXb . We will send a short sequence of on-boarding emails over the next week to help you learn about the organization and prepare for a meeting. You will also get quarterly update emails and alerts for special events."

Start by reviewing the requested Mailchimp automation and the Meetup Welcome message. Confirm the onboarding sequence, quarterly updates, and special-event alerts can be delivered to new sign-ups, and that the Welcome message contains the supplied email-list wording.

Written by the indexing model from the issue text.