style: add comments to the public methods and members in the root package.

audio.go

@@ -1,10 +1,18 @@
 package sointu
 
+// AudioSink represents something where we can send audio e.g. audio output.
+// WriteAudio should block if not ready to accept audio e.g. buffer full.
 type AudioSink interface {
 	WriteAudio(buffer []float32) error
 	Close() error
 }
 
+// AudioContext represents the low-level audio drivers. There should be at most
+// one AudioContext at a time. The interface is implemented at least by
+// oto.OtoContext, but in future we could also mock it.
+//
+// AudioContext is used to create one or more AudioSinks with Output(); each can
+// be used to output separate sound & closed when done.
 type AudioContext interface {
 	Output() AudioSink
 	Close() error