Index: wp-admin/update-core.php
===================================================================
--- wp-admin/update-core.php	(revision 26234)
+++ wp-admin/update-core.php	(working copy)
@@ -517,6 +517,11 @@
 	if ( $core || $plugins || $themes )
 		list_translation_updates();
 	unset( $core, $plugins, $themes );
+        /**
+         * Fires after the core, plugin and theme update forms.
+         *
+         * @since 2.9.0
+         */
 	do_action('core_upgrade_preamble');
 	echo '</div>';
 	include(ABSPATH . 'wp-admin/admin-footer.php');
@@ -625,5 +630,14 @@
 	require_once( ABSPATH . 'wp-admin/admin-footer.php' );
 
 } else {
+        /**
+         * Fires when none of the default conditions matches the action
+         * parameter in the url.
+         *
+         * The dynamic portion of the hook name, $action, refers to the action
+         * paremeter in the url.
+         *
+         * @since 3.2.0
+         */
 	do_action('update-core-custom_' . $action);
-}
+}
\ No newline at end of file