New automated email to students who have attended 5 workshops

[KimberleyCook]

Description of the issue 📄

We would like to send a celebratory automated email to students who have attended 5 workshops.

Would it also be possible to send one after 10, 15, 20 ETC???

If you'd like to implement this new feature please drop me a DM on Slack for the copy needed.

Screenshots 📷

Steps to fix 🛠

To do 📋

• [ ] Claim this issue (comment below, or assign yourself if you are part of the codebar org)
• [ ] Fork and clone the repository
• [ ] Update the relevant files. Follow the steps to fix section in this issue.
• [ ] Commit your changes as one commit. Use the title of this issue as your commit message
• [ ] Submit a pull request
• [ ] Mention this issue in the PR description by including it's number
• [ ] Have your pull request reviewed & merged by a codebar team member