Broken link in Definition of "focusable"

[Jym77]

https://act-rules.github.io/glossary/#focusable links to https://html.spec.whatwg.org/#specially-focusable which doesn't seem to exist.

I do not know what it was supposed to link.
@jeeyyy you changed that link back in https://github.com/act-rules/act-rules.github.io/pull/854/files#diff-e800929b705e347af7d28f9b7d1d1f0bR6 Do you remember what it was supposed to be?

[jeeyyy]

Was the specially focusable removed from the living standard spec? Have to do some digging to find what the new link would be.

@Jym77 - any ideas how I can find previous iterations of the spec?