Create Welcome to AtD email template

### Overview
When folx join the project, we should be able to send them a getting started package to help them navigate the project space, understand AtD, and get them to their first commit as quickly as possible. We need to create an email template that we can send to new contributors to help get them started.

### Dependencies
We first need organized, functioning onboarding wiki pages
- [x] #221
- [x] #222
- [x] #252
- [x] #279

### Action Items

- [ ] Create draft of template in AtD gmail account
- [ ] include links to onboarding wiki pages as needed
- [ ] Review with team to see if they feel it is too short, too long, and has the right information
- [ ] Update with team input

### Resources/Instructions
[How to create an email template in gmail](https://www.dragapp.com/blog/email-templates-gmail/)