Docs: Cross-reference parent classes in DocBlocks for upgrader classes moved to their own files in 4.6

See #36618. See #37318.

Built from https://develop.svn.wordpress.org/trunk@38023


git-svn-id: http://core.svn.wordpress.org/trunk@37964 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/class-theme-installer-skin.php

@@ -12,6 +12,8 @@
  *
  * @since 2.8.0
  * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader-skins.php.
+ *
+ * @see WP_Upgrader_Skin
  */
 class Theme_Installer_Skin extends WP_Upgrader_Skin {
 	public $api;