Removing a ".auth" file revokes a client access to the service but the
rendezvous circuit is not closed service side because the service simply
doesn't know which circuit is for which client.

This commit notes in the man page that to fully revoke a client access to the
service, the tor process should be restarted.

Closes #28275

Signed-off-by: David Goulet <dgoulet@torproject.org>