docs: override default excluded filenames

fix #8009

docs/_docs/structure.md

@@ -206,3 +206,11 @@ An overview of what each of these does:
   </tbody>
 </table>
 </div>
+
+Every file or directory beginning with the following characters: `.`, `_ `, `#` or `~` in the `source` directory will not be included in the `destination` folder. Such paths will have to be explicitly specified via the config file in the `include` directive to make sure they're copied over:
+
+```yaml
+include:
+ - _pages
+ - .htaccess
+ ```