Add comment about size of generated previews of filebrowser thumnails.

source/blender/editors/space_file/filelist.c

@@ -1294,6 +1294,8 @@ static void filelist_cache_preview_runf(TaskPool *__restrict pool, void *taskdat
   }
 
   IMB_thumb_path_lock(preview->path);
+  /* Always generate biggest preview size for now, it's simpler and avoids having to re-generate in
+   * case user switch to a biger preview size... */
   preview->img = IMB_thumb_manage(preview->path, THB_LARGE, source);
   IMB_thumb_path_unlock(preview->path);