currently I find myself often doing
grep -R ClassName juce/modules
to find out the module I have to add to my project to use a particular class. AFAIK you’re using Doxygen for the documentaion. maybe you could use
/// @defgroup juce_audio_utils Classes for audio-related GUI and miscellaneous tasks. and /// @ingroup juce_audio_utils
This adds a link to the group below the classname heading and also adds a modules section to the doxygen navigation.