Currently, BETA classes do not get docs generated for them, and they are not referenced in automatic documentation (which is good).
However, if some stable class references a BETA class, a link is created, which is broken.

We should turn the link into plain text and add a note explaining that that class is still BETA: (object still in beta stage).

This is already done in the C# documentation:
https://enlightenment.github.io/www-content/gh-pages/api/csharp/api/Efl.Ui.Box.html
(Look for the link to Efl.Gfx.IArrangement).