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