new config guest_redirection added

docs/configuration/basic.md

@@ -23,6 +23,7 @@ Note: if you've made a mistake in configuration file (forgot to close a quote?)
         'default_archive_name' => 'archive.zip',
         'editable' => ['.txt', '.css', '.js', '.ts', '.html', '.php'],
         'date_format' => 'YY/MM/DD hh:mm:ss', // see: https://momentjs.com/docs/#/displaying/format/
+        'guest_redirection' => '', // useful for external auth adapters
     ],
 ```