The `cyrusless_sasl` authenticator example failed to explicitly fail if
no result was found from the lookup. Using `server_secret`, we should
_always_ fail instead of expanding to an empty string.
Doc-fix only.
driver = cram_md5
public_name = CRAM-MD5
server_secret = ${lookup{$auth1:mail.example.org:userPassword}\
driver = cram_md5
public_name = CRAM-MD5
server_secret = ${lookup{$auth1:mail.example.org:userPassword}\
+ dbmjz{/etc/sasldb2}{$value}fail}
server_set_id = $auth1
.endd
server_set_id = $auth1
.endd