qapi/migration: Add missing tls-authz documentation

As reported in Markus's recent enforcement series on qapi doc [1], we
accidentally miss one entry for tls-authz.  Add it.

[1] https://lore.kernel.org/r/20240205074709.3613229-1-armbru@redhat.com

Cc: Daniel P. Berrangé <berrange@redhat.com>
Cc: Fabiano Rosas <farosas@suse.de>
Reported-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-ID: <20240207032836.268183-1-peterx@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[Update of qapi/pragma.json squashed in, commit message adjusted]
2 files changed