Add/update links & add links to default home page

Closes #3498635

recipes/drupal_cms_starter/content/menu_link_content/welcome-20-choose-add-ons.yml

+_meta:
+  version: '1.0'
+  entity_type: menu_link_content
+  uuid: abebe9f4-6aad-414d-899e-b172c6fd226f
+  bundle: menu_link_content
+  default_langcode: en
+default:
+  enabled:
+    -
+      value: true
+  title:
+    -
+      value: 'Choose recommended add-ons'
+  menu_name:
+    -
+      value: welcome
+  link:
+    -
+      uri: 'internal:/admin/modules/browse/recipes'
+      title: ''
+      options: {  }
+  external:
+    -
+      value: false
+  rediscover:
+    -
+      value: true
+  weight:
+    -
+      value: 20
+  expanded:
+    -
+      value: false
+  revision_translation_affected:
+    -
+      value: true

[Jim Birch]

-      value: 'Choose recommended add-ons'
+      value: 'Choose recommended add-on recipes'

[Pamela Barone]

I think I'll try to hold the line against introducing 'Recipes' to the UI until all is lost!