Fix missing doc in config.h

include/assimp/config.h.in

@@ -981,8 +981,12 @@ enum aiComponent
 
 #define AI_CONFIG_EXPORT_XFILE_64BIT "EXPORT_XFILE_64BIT"
 
-/**
- *
+/** @brief Specifies whether the assimp export shall be able to export point clouds
+ * 
+ *  When this flag is not defined the render data has to contain valid faces.
+ *  Point clouds are only a collection of vertices which have nor spatial organization
+ *  by a face and the validation process will remove them. Enabling this feature will
+ *  switch off the flag and enable the functionality to export pure point clouds.
  */
 #define AI_CONFIG_EXPORT_POINT_CLOUDS "EXPORT_POINT_CLOUDS"