Docs: Clarify wp-includes/update.php main docblock description.

Props costdev, audrasjb.
See #55646.


git-svn-id: https://develop.svn.wordpress.org/trunk@54116 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/update.php

@@ -1,6 +1,6 @@
 <?php
 /**
- * A simple set of functions to check our Version Update service.
+ * A simple set of functions to check the WordPress.org Version Update service.
  *
  * @package WordPress
  * @since 2.3.0