Add documentation in preparation for WAV, FLAC and MP3 amalgamation.

miniaudio.h

@@ -474,6 +474,15 @@ Build Options
 #define MA_NO_ENCODING
   Disables encoding APIs.
 
+#define MA_NO_WAV
+  Disables the built-in WAV decoder and encoder.
+
+#define MA_NO_FLAC
+  Disables the built-in FLAC decoder.
+
+#define MA_NO_MP3
+  Disables the built-in MP3 decoder.
+
 #define MA_NO_DEVICE_IO
   Disables playback and recording. This will disable ma_context and ma_device APIs. This is useful if you only want to use miniaudio's data conversion and/or
   decoding APIs.