added a missing ref

[Henonicks]

[ Please outline your change here. Be sure to check the checkboxes below. ]

Documentation change checklist

• [x] My documentation changes follow the docs style guide and any code examples follow the coding style guide.
• [x] I tested that my change works before raising the PR (via running doxygen, and testing examples).
• [x] I have not moved any existing pages or changed any existing URLs without strong justification as to why.
• [x] I have not generated content using AI or a desktop utility such as grammarly.

[netlify[bot]]

✅ Deploy Preview for dpp-dev ready!

Name	Link
🔨 Latest commit	9d2c8461baf118c4a02efce98201667e6f6e91d2
🔍 Latest deploy log	https://app.netlify.com/sites/dpp-dev/deploys/66829c76ef8c78000744d9b6
😎 Deploy Preview	https://deploy-preview-1179--dpp-dev.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.