Issue #3420356 by dww, thursday_bw, Kanchan Bhogade, smustgrave, benjifisher, catch, alexpott: Add link to Update module documentation about installer settings

(cherry picked from commit 2e08112eaa)

core/lib/Drupal/Core/Installer/Form/SiteConfigureForm.php

@@ -223,7 +223,7 @@ class SiteConfigureForm extends ConfigFormBase {
     $form['update_notifications'] = [
       '#type' => 'fieldgroup',
       '#title' => $this->t('Update notifications'),
-      '#description' => $this->t('When checking for updates, anonymous information about your site is sent to <a href="@drupal">Drupal.org</a>.', ['@drupal' => 'https://drupal.org']),
+      '#description' => $this->t('When checking for updates, your site automatically sends anonymous information to Drupal.org. See the <a href="@update-module-docs" target="_blank">Update module documentation</a> for details.', ['@update-module-docs' => 'https://www.drupal.org/node/178772']),
       '#access' => empty($install_state['config_install_path']),
     ];
     $form['update_notifications']['enable_update_status_module'] = [