[docs] Fix broken anchor link to w3.org

Author: oliviertassinari

docs/data/base/components/button/button.md

@@ -142,7 +142,7 @@ Instead, `aria-disabled` is used, which makes the Button focusable.
 
 This should be used whenever the disabled Button needs to be read by screen readers.
 
-Base UI uses this prop internally in [menu items](/base-ui/react-menu/), making it possible to use the keyboard to navigate to disabled items (in compliance with [ARIA guidelines](https://www.w3.org/WAI/ARIA/apg/practices/keyboard-interface/#x6-7-focusability-of-disabled-controls)).
+Base UI uses this prop internally in [menu items](/base-ui/react-menu/), making it possible to use the keyboard to navigate to disabled items (in compliance with [ARIA guidelines](https://www.w3.org/WAI/ARIA/apg/practices/keyboard-interface/#focusabilityofdisabledcontrols)).
 
 The following demo shows how the `focusableWhenDisabled` prop works—use the <kbd class="key">Tab</kbd> key to navigate within this document to see that only the second Button accepts the focus: