add calendar migration

calendar/sogo.markdown

@@ -42,3 +42,15 @@ https://sogo.phys.ethz.ch/SOGo/dav/
 ### ActiveSync sync URL
 
 https://sogo.phys.ethz.ch/Microsoft-Server-ActiveSync
+
+Calendar migration from eGroupware
+----------------------------------
+
+### Export your calendar data from eGroupware
+[[!img /media/sogo/epl-export-1.png size="450x"]]
+[[!img /media/sogo/epl-export-2.png size="450x"]]
+[[!img /media/sogo/epl-export-3.png size="450x"]]
+
+### Import your calendar data into SOGo
+[[!img /media/sogo/sogo-import-1.png size="450x"]]
+[[!img /media/sogo/sogo-import-2.png size="450x"]]