update demo link for Kopano

Hi, the demo link for Kopano was missing the http and is therefore broken. Fix attached.

README.md

@@ -565,7 +565,7 @@ Some [Groupware](#groupware) solutions also feature file sharing and synchroniza
   * [egroupware](http://www.egroupware.org/) - Software suite including calendars, address books, notepad, project management tools, client relationship management tools (CRM), knowledge management tools, a wiki and a CMS. ([Source Code](https://github.com/EGroupware/egroupware)) `GPLv2` `PHP`
   * [Horde](http://www.horde.org/) - The Horde Project is about creating high quality Open Source applications and libraries, based on PHP and the Horde Framework. ([Demo](http://demo.horde.org/login.php), [Source Code](https://github.com/horde/horde)) `GPLv2`
   * [Kolab](https://kolab.org/) - Kolab community is a unified communication and collaboration system. ([Source Code](https://git.kolab.org/)) `Various FLOSS Licenses` `C++/Python/PHP`
-  * [Kopano](https://kopano.com/) - Groupware suite including e-mail, calendars, tasks, todos and notes. Featuring a modern WebApp, DeskApp and mobile access over Z-Push/ActiveSync. ([Demo](demo.kopano.com), [Source Code](https://stash.kopano.io)) `AGPLv3` `C/Python/PHP`
+  * [Kopano](https://kopano.com/) - Groupware suite including e-mail, calendars, tasks, todos and notes. Featuring a modern WebApp, DeskApp and mobile access over Z-Push/ActiveSync. ([Demo](http://demo.kopano.com), [Source Code](https://stash.kopano.io)) `AGPLv3` `C/Python/PHP`
   * [Mayan EDMS](http://www.mayan-edms.com) - Free Open Source Electronic Document Management System. An electronic vault for your documents with preview generation, OCR, and automatic categorization among other features. ([Demo](http://demo.mayan-edms.com), [Source Code](https://gitlab.com/mayan-edms/mayan-edms)) `Apache` `Python/Django`
   * [Openmeetings](https://openmeetings.apache.org/index.html). ([Source Code](https://svn.apache.org/viewvc/openmeetings/trunk/singlewebapp/)) - Openmeetings provides video conferencing, instant messaging, white board, collaborative document editing and other groupware tools using API functions of the Red5 Streaming Server for Remoting and Streaming. `Apache 2.0`  `Java`
   * [Sogo](http://www.sogo.nu/) - SOGo offers multiple ways to access the calendaring and messaging data. CalDAV, CardDAV, GroupDAV, as well as ActiveSync, including native Outlook compatibility and web interface. ([Demo](http://www.sogo.nu/tour/online_demo.html), [Source Code](http://www.sogo.nu/development/source_code.html)) `GPLv1/LGPLv2` `Objective-C`