Document the correct web-root default value

Verified this still applies

Checked \Drupal\Composer\Plugin\Scaffold\ScaffoldOptions::__construct

    $this->options['locations'] += [
      'project-root' => '.',
      'web-root' => '.',
    ];

So still seems valid.

Should we explain what . means? Something like

If a web-root is not explicitly defined, then it will default to `.`, the same
directory as the composer.json file.

Don't think it could hurt. If you make the change I can stay in the reviewer role.

Sorry not sure how this fell off the radar

Committed and pushed to 10.1.x,10.0.x and 9.5.x. Thanks!

Automatically closed - issue fixed for 2 weeks with no activity.