MAN PAGE: modified sssd-ldap.5.xml for sssd ticket #2451
https://fedorahosted.org/sssd/ticket/2451
Added a configuration example at the bottom for
'ldap_access_order = lockout'. Also added a line
to note that 'ldap_access_provider = ldap' must
be specified for this feature to work.
Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>