example from README does not work as-is - syntax error

``` shell
(fosdem-volunteers)emanuil@midori:~/software/secure-smtpd$ python --version
Python 2.7.6

(fosdem-volunteers)emanuil@midori:~/software/secure-smtpd$ pip freeze | grep smtpd
secure-smtpd==3.0.0

(fosdem-volunteers)emanuil@midori:~/software/secure-smtpd$ cat run.py
from secure_smtpd import SMTPServer, FakeCredentialValidator
SMTPServer(
self,
('0.0.0.0', 465),
None,
require_authentication=True,
ssl=True,
certfile='examples/server.crt',
keyfile='examples/server.key',
credential_validator=FakeCredentialValidator(),
)
asyncore.loop()

(fosdem-volunteers)emanuil@midori:~/software/secure-smtpd$ python run.py
Traceback (most recent call last):
File "run.py", line 3, in
self,
NameError: name 'self' is not defined
```

Open the README example referenced in the issue and compare it with the shown run.py and traceback. Correct the example so it can be run without the reported NameError, then verify the documented command no longer produces that error.

Written by the indexing model from the issue text.