[doc] update RtAudioFormat description to match code

doc/doxygen/probe.txt

@@ -54,12 +54,12 @@ The following data formats are defined and fully supported by RtAudio:
 
 \code
   typedef unsigned long RtAudioFormat;
-  static const RtAudioFormat  RTAUDIO_SINT8;   // Signed 8-bit integer
-  static const RtAudioFormat  RTAUDIO_SINT16;  // Signed 16-bit integer
-  static const RtAudioFormat  RTAUDIO_SINT24;  // Signed 24-bit integer (lower 3 bytes of 32-bit signed integer.)
-  static const RtAudioFormat  RTAUDIO_SINT32;  // Signed 32-bit integer
-  static const RtAudioFormat  RTAUDIO_FLOAT32; // 32-bit float normalized between +/- 1.0
-  static const RtAudioFormat  RTAUDIO_FLOAT64; // 64-bit double normalized between +/- 1.0
+  static const RtAudioFormat RTAUDIO_SINT8 = 0x1;    // 8-bit signed integer.
+  static const RtAudioFormat RTAUDIO_SINT16 = 0x2;   // 16-bit signed integer.
+  static const RtAudioFormat RTAUDIO_SINT24 = 0x4;   // 24-bit signed integer.
+  static const RtAudioFormat RTAUDIO_SINT32 = 0x8;   // 32-bit signed integer.
+  static const RtAudioFormat RTAUDIO_FLOAT32 = 0x10; // Normalized between plus/minus 1.0.
+  static const RtAudioFormat RTAUDIO_FLOAT64 = 0x20; // Normalized between plus/minus 1.0.
 \endcode
 
 The \c nativeFormats member of the RtAudio::DeviceInfo structure is a bit mask of the above formats which are natively supported by the device.  However, RtAudio will automatically provide format conversion if a particular format is not natively supported.  When the \c probed member of the RtAudio::DeviceInfo structure is false, the remaining structure members are undefined and the device is probably unusable.