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

core/themes/classy/README.txt

@@ -0,0 +1,17 @@
+ABOUT CLASSY
+-----------
+
+Classy is a base theme that provides many classes in its markup. For cleaner
+markup (fewer classes), the default Stable base theme can be used instead.
+
+To use Classy as your base theme, set the 'base theme' in your theme's .info.yml
+file to "classy":
+  base theme: classy
+
+See https://www.drupal.org/theme-guide/8/classy for more information on using
+the Classy theme.
+
+ABOUT DRUPAL THEMING
+--------------------
+
+See https://www.drupal.org/theme-guide/8 for more information on Drupal theming.

core/themes/classy/css/components/dialog.css

@@ -56,7 +56,7 @@
   top: 48.5%;
   z-index: 1000;
   background-color: #232323;
-  background-image: url(loading-small.gif);
+  background-image: url(../../../../misc/loading-small.gif);
   background-position: center center;
   background-repeat: no-repeat;
   border-radius: 7px;

core/themes/classy/templates/form/container.html.twig

@@ -5,8 +5,10 @@
  *
  * Used for grouped form items. Can also be used as a theme wrapper for any
  * renderable element, to surround it with a <div> and HTML attributes.
- * See the @link forms_api_reference.html Form API reference @endlink for more
- * information on the #theme_wrappers render array property.
+ * See \Drupal\Core\Render\Element\RenderElement for more
+ * information on the #theme_wrappers render array property, and
+ * \Drupal\Core\Render\Element\container for usage of the container render
+ * element.
  *
  * Available variables:
  * - attributes: HTML attributes for the containing element.