The `AudioEffectRecord` effect has no microphone capture-specific functionality--it can be used with any audio bus.
This patch attempts to clarify this fact (so people like me who want to capture audio output know they're in the right place) while still providing a pointer use of the effect with `AudioStreamMicrophone` for microphone capture.
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.
