fIx table headers

[github-actions[bot]]

Automated changes by create-pull-request GitHub action

[netlify[bot]]

✅ Deploy Preview for nature-of-code-2nd-edition ready!

Name	Link
🔨 Latest commit	acbcbc53f1ba8eb825ef796af6f8286f5494aff2
🔍 Latest deploy log	https://app.netlify.com/sites/nature-of-code-2nd-edition/deploys/660c9bfdfe13140008bf9adb
😎 Deploy Preview	https://deploy-preview-930--nature-of-code-2nd-edition.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[netlify[bot]]

✅ Deploy Preview for nature-of-code-pdf ready!

Name	Link
🔨 Latest commit	acbcbc53f1ba8eb825ef796af6f8286f5494aff2
🔍 Latest deploy log	https://app.netlify.com/sites/nature-of-code-pdf/deploys/660c9bfdf2c30f0008fc896a
😎 Deploy Preview	https://deploy-preview-930--nature-of-code-pdf.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[shiffman]

See #929