Update to Drupal 8.0.2. For more information, see https://www.drupal.org/drupal-8.0.2-release-notes

core/modules/help/src/Plugin/Block/HelpBlock.php

@@ -89,6 +89,9 @@ class HelpBlock extends BlockBase implements ContainerFactoryPluginInterface {
    *
    * @param \Symfony\Component\HttpFoundation\Request $request
    *   The current request.
+   *
+   * @return string
+   *   Help text of the matched route item as HTML.
    */
   protected function getActiveHelp(Request $request) {
     // Do not show on a 403 or 404 page.

core/modules/help/src/Tests/HelpTest.php

@@ -86,8 +86,8 @@ class HelpTest extends WebTestBase {
   /**
    * Verifies the logged in user has access to the various help nodes.
    *
-   * @param integer $response
-   *   An HTTP response code.
+   * @param int $response
+   *   (optional) An HTTP response code. Defaults to 200.
    */
   protected function verifyHelp($response = 200) {
     $this->drupalGet('admin/index');