docs: direct link to pages returns a 404

[codymullins]

The docs page is hosted on Github Pages. When someone enters the docs via the base URL, all navigation works fine.

However, linking to a page that is not the base URL returns a 404. It appears to be possible to intercept this on the 404 page.

References https://github.com/rafgraph/spa-github-pages https://blog.elmah.io/blazor-wasm-404-error-and-fix-for-github-pages/