fix cyrus-imapd URL

README.md

@@ -349,7 +349,7 @@ _MTAs / SMTP servers_
 
 _MDAs - IMAP/POP3 software_
 
-- [Cyrus IMAP/POP3](http://cyrusimap.org/) - Intended to be run on sealed servers, where normal users are not permitted to log in. ([Source Code](https://github.com/cyrusimap/cyrus-imapd )) `BSD-3-Clause-Attribution` `C`
+- [Cyrus IMAP/POP3](https://www.cyrusimap.org/) - Intended to be run on sealed servers, where normal users are not permitted to log in. ([Source Code](https://github.com/cyrusimap/cyrus-imapd )) `BSD-3-Clause-Attribution` `C`
 - [Dovecot](http://www.dovecot.org/) - IMAP and POP3 server written primarily with security in mind. ([Source Code](https://github.com/dovecot/core)) `MIT/LGPL-2.1` `C`
 - [Piler](http://www.mailpiler.org/wiki/start) - feature rich open source email archiving solution. ([Source Code](https://bitbucket.org/jsuto/piler)) `GPL-3.0` `C`