Update to Drupal 8.1.0. For more information, see https://www.drupal.org/drupal-8.1.0-release-notes

core/modules/system/templates/entity-add-list.html.twig

@@ -0,0 +1,30 @@
+{#
+/**
+ * @file
+ * Default theme implementation to present a list of available bundles.
+ *
+ * Available variables:
+ *   - bundles: A list of bundles, each with the following properties:
+ *     - label: Bundle label.
+ *     - description: Bundle description.
+ *     - add_link: Link to create an entity of this bundle.
+ *   - add_bundle_message: The message shown when there are no bundles. Only
+ *                         available if the entity type uses bundle entities.
+ *
+ * @see template_preprocess_entity_add_list()
+ *
+ * @ingroup themeable
+ */
+#}
+{% if bundles is not empty %}
+  <dl>
+    {% for bundle in bundles %}
+      <dt>{{ bundle.add_link }}</dt>
+      <dd>{{ bundle.description }}</dd>
+    {% endfor %}
+  </dl>
+{% elseif add_bundle_message is not empty %}
+  <p>
+    {{ add_bundle_message }}
+  </p>
+{% endif %}

core/modules/system/templates/install-page.html.twig

@@ -28,7 +28,7 @@
 
     <main role="main">
       {% if title %}
-        <h1>{{ title }}</h1>
+        <h2>{{ title }}</h2>
       {% endif %}
       {{ page.highlighted }}
       {{ page.content }}

core/modules/system/templates/links.html.twig

@@ -13,7 +13,6 @@
  *     to l() as its $options parameter.
  *   - attributes: (optional) HTML attributes for the anchor, or for the <span>
  *     tag if no 'href' is supplied.
- *   - link_key: The link CSS class.
  * - heading: (optional) A heading to precede the links.
  *   - text: The heading text.
  *   - level: The heading level (e.g. 'h2', 'h3').
@@ -43,8 +42,8 @@
     {%- endif -%}
   {%- endif -%}
   <ul{{ attributes }}>
-    {%- for key, item in links -%}
-      <li{{ item.attributes.addClass(key|clean_class) }}>
+    {%- for item in links -%}
+      <li{{ item.attributes }}>
         {%- if item.link -%}
           {{ item.link }}
         {%- elseif item.text_attributes -%}