Merge branch 'mc/http-emptyauth-negotiate-fix' into next

The 'http.emptyAuth=auto' configuration now correctly attempts
Negotiate authentication before falling back to manual credentials.
This allows seamless Kerberos ticket-based authentication without
requiring users to explicitly set 'http.emptyAuth=true'.

* mc/http-emptyauth-negotiate-fix:
  doc: clarify http.emptyAuth values