[Bug]: Sidebar defaults to "Learn" when opening Reference pages

[mootari]

📝 Issue Description

When accessing a reference page directly (i.e., without internal navigation) the sidebar shows the "Learn" nav menu instead of "Reference".

📋 On which page(s) it occurs

All reference pages, e.g. https://docs.solidjs.com/reference/secondary-primitives/create-selector

🤔 Expected Behavior

Sidebar nav "Reference" is shown.

👀 Current Behavior

Sidebar nav "Learn" is shown.

🖥️ Browser

Chrome 150, Firefox 152

📄 Additional Information

No response