Restructured the source code in the Playdate bindings target.

Sources/PlaydateKit/Sound/Aliases/MIDINote.swift

@@ -0,0 +1,5 @@
+extension Sound {
+    /// A note as a MIDI note number, where 60 is middle C. Fractional values
+    /// are valid.
+    public typealias MIDINote = Float
+}