add link to trac

Author: soderlind

README.md

@@ -111,7 +111,7 @@ You can use the following filters to override the defaults:
 
 A demo is available in [WordPress Playground](https://playground.wordpress.net/?blueprint-url=https://raw.githubusercontent.com/soderlind/super-admin-all-sites-menu/refs/heads/main/blueprint.json). It's a bit slow loading, 50 sub sites are added.
 
-- If you disable Super Admin All Sites Menu in the Main Site plugins menu, you'll see the WP Admin Bar My Sites menu doesen't allow you to scroll and see all site. This an old bug in WordPress.
+- If you disable Super Admin All Sites Menu in the Main Site plugins menu, you'll see the WP Admin Bar My Sites menu doesen't allow you to scroll and see all site. This an 14 years old (!) [bug in WordPress](https://core.trac.wordpress.org/ticket/15317).
 
 - If you activate the Restricted Site Access plugin (included), you'll see a red icon next to the site name. ATM, this only work on the main site due to [issues with WordPress Playground](https://github.com/WordPress/wordpress-playground/issues/2054).