For the time being we don't support writing a description for those, preferring
having all details in the method's description.
Using self-closing tags saves half the lines, and prevents contributors from
thinking that they should write the argument or return documentation there.
We already removed it from the online docs with #35132.
Currently it can only be "Built-In Types" (Variant types) or "Core"
(everything else), which is of limited use.
We might also want to consider dropping it from `ClassDB` altogether
in Godot 4.0.
- Add a link to the audio generator demo in AudioStreamGenerator
and AudioStreamGeneratorPlayback.
- Mention that signed PCM8 data is expected in AudioStreamSample
(and how to convert unsigned PCM8 to signed PCM8).
