Docs: Fix note about not using new functions in update-core.php and class-core-upgrader.php.

Props costdev.
See #62165.

git-svn-id: https://develop.svn.wordpress.org/trunk@59182 602fd350-edb4-49c9-b593-d223f7449a82

Author: azaozz

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

@@ -13,10 +13,9 @@
  * It allows for WordPress to upgrade itself in combination with
  * the wp-admin/includes/update-core.php file.
  *
- * Note: newly introduced functions and methods cannot be used here.
- * All functions must be present in both the previous version being upgraded from,
- * and the later version that's being installed (e.g. when rolling back Core)
- * as this file is used in both.
+ * Note: Newly introduced functions and methods cannot be used here.
+ * All functions must be present in the previous version being upgraded from
+ * as this file is used there too.
  *
  * @since 2.8.0
  * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader.php.

src/wp-admin/includes/update-core.php

@@ -2,10 +2,9 @@
 /**
  * WordPress core upgrade functionality.
  *
- * Note: newly introduced functions and methods cannot be used here.
- * All functions must be present in both the previous version being upgraded from,
- * and the later version that's being installed (e.g. when rolling back Core)
- * as this file is used in both.
+ * Note: Newly introduced functions and methods cannot be used here.
+ * All functions must be present in the previous version being upgraded from
+ * as this file is used there too.
  *
  * @package WordPress
  * @subpackage Administration