Inconsistent Documentation

Configuring the private file path.
Looking up
/admin/config/media/file-system
one can read

Private file system path
../priv
An existing local file system path for storing private files. It should be writable by Drupal and not accessible over the web. This must be changed in settings.php

The section in settings.php reads:

A local file system path where private files will be stored. This directory
* must be absolute, outside of the Drupal installation directory and not
* accessible over the web.

Using an absolute path, such as /var/www/html/priv, makes (at least) webform cough -- Drupal seems to be fine.
One has to set
$settings['file_private_path'] = '../priv';
to keep Drupal AND webform happy.

It would be nice if the word "absolute" in settings.php would be replaced by "relative to the directory in which index.php resides" to eliminate some guesswork from less experienced file system users …

Same should be done for temp and sync