"Read more about the UI Builder" leads to a missing page

How to reproduce:
1. Create a new Unity project
2. Go to Window -> UI Toolkit -> UI Builder
3. On the right, navigate to the UI Builder start tab
4. Click "Read more about the UI Builder" and observe the results

Expected results: The documentation opens
Actual results: The page is missing

Reproducible with: 6000.4.0a1, 6000.4.0a2
Not reproducible with: 6000.0.60f1, 6000.3.0a6, 6000.3.0b4

Reproducible on: macOS Sequoia 15.6 (M1)
Not reproducible on: No other environment tested