✨ feat: fill in homepage project cards

[JoshuaKGoldberg]

PR Checklist

• [x] Addresses an existing open issue: fixes #18
• [x] That issue was marked as accepting prs
• [x] Steps in CONTRIBUTING.md were taken

Overview

Now that I've filled out projects for the the first ~half of the chapters, there's enough data to not have homepage TBDs.