Multisite: Update @since tags for site meta introduction.

Fixes #37923. Fixes #40229.

Built from https://develop.svn.wordpress.org/trunk@44467


git-svn-id: http://core.svn.wordpress.org/trunk@44298 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/functions.php

@@ -4912,7 +4912,7 @@ function global_terms_enabled() {
  * a setting for the main network, making it essentially a global setting. Subsequent requests
  * will refer to this setting instead of running the query.
  *
- * @since 5.0.0
+ * @since 5.1.0
  *
  * @global wpdb $wpdb WordPress database abstraction object.
  *