Docs: Supplement a changelog entry in the DocBlock for the $id property in WP_Network.

See [37657] for where access was changed from public to private.
See [37870] for where the type was changed from `string` to `int`.

See #36717.


git-svn-id: https://develop.svn.wordpress.org/trunk@37919 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-network.php

@@ -27,7 +27,9 @@ class WP_Network {
 	 * Network ID.
 	 *
 	 * @since 4.4.0
-	 * @since 4.6.0 Type changed from string to int.
+	 * @since 4.6.0 Converted from public to private to explicitly enable more intuitive
+	 *              access via magic methods. As part of the access change, the type was
+	 *              also changed from `string` to `int`.
 	 * @access private
 	 * @var int
 	 */