channel_layout: doxy: merge functions with macros

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavutil/channel_layout.h

@@ -79,7 +79,7 @@
 
 /**
  * @}
- * @defgroup channel_mask_c Audio channel convenience macros
+ * @defgroup channel_mask_c Audio channel layouts
  * @{
  * */
 #define AV_CH_LAYOUT_MONO              (AV_CH_FRONT_CENTER)
@@ -121,10 +121,6 @@ enum AVMatrixEncoding {
     AV_MATRIX_ENCODING_NB
 };
 
-/**
- * @}
- */
-
 /**
  * Return a channel layout id that matches name, or 0 if no match is found.
  *
@@ -219,6 +215,7 @@ int av_get_standard_channel_layout(unsigned index, uint64_t *layout,
                                    const char **name);
 
 /**
+ * @}
  * @}
  */