Issue #2940027 by jmsosso: Add change record to @deprecated for AccountInterface

(cherry picked from commit 6b6bc91)

Author: alexpott

lib/Drupal/Core/Session/AccountInterface.php

@@ -115,6 +115,8 @@ public function getPreferredAdminLangcode($fallback_to_default = TRUE);
    * @deprecated in Drupal 8.0.0, will be removed before Drupal 9.0.0.
    *   Use \Drupal\Core\Session\AccountInterface::getAccountName() or
    *   \Drupal\user\UserInterface::getDisplayName() instead.
+   *
+   * @see https://www.drupal.org/node/2572493
    */
   public function getUsername();