Cleanup: add missing doxy sections in customdata

source/blender/blenkernel/intern/customdata.cc

@@ -765,7 +765,12 @@ static void layerFree_grid_paint_mask(void *data, int count, int UNUSED(size))
   }
 }
 
-/* --------- */
+/** \} */
+
+/* -------------------------------------------------------------------- */
+/** \name Callbacks for (#MLoopCol, #CD_PROP_BYTE_COLOR)
+ * \{ */
+
 static void layerCopyValue_mloopcol(const void *source,
                                     void *dest,
                                     const int mixmode,
@@ -954,6 +959,12 @@ static int layerMaxNum_mloopcol()
   return MAX_MCOL;
 }
 
+/** \} */
+
+/* -------------------------------------------------------------------- */
+/** \name Callbacks for (#MLoopUV, #CD_MLOOPUV)
+ * \{ */
+
 static void layerCopyValue_mloopuv(const void *source,
                                    void *dest,
                                    const int mixmode,