Add explicit link to the installation being updated in debugging emails. see #22704.

git-svn-id: https://develop.svn.wordpress.org/trunk@25770 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/includes/class-wp-upgrader.php

@@ -1796,6 +1796,8 @@ class WP_Automatic_Upgrader {
 		$body = array();
 		$failures = 0;
 
+		$body[] = 'WordPress site: ' . network_home_url( '/' );
+
 		// Core
 		if ( isset( self::$upgrade_results['core'] ) ) {
 			$result = self::$upgrade_results['core'][0];