thunderbird: rm egroupware reference

calendar/thunderbird.markdown

@@ -7,7 +7,6 @@ Mozilla's Thunderbird with the Lightning calendar plugin works very well with SO
   * In the 'Calendars' tab, right click and choose 'New Calendar'. Next. Select 'On the Network'. Next. CalDAV format, Location: https://sogo.phys.ethz.ch/SOGo/dav - hit next. Choose a name and a color. Next. Finish.
   * [[!img /media/sogo/egw_location_url.png]]
   * When Lightning asks for username and password, use your D-PHYS login and password.
-  * Appointments and Tasks will now be synchronized between your Thunderbird calendar and eGroupware.
 
 Support multiple users on the same server
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