[calendar] Added missing documentation about freeing memory
[calendar] Added missing documentation about freeing memory

GNOME/libgdata,Pecisk/libgdata-gtasks,pwithnall/libgdata,Pecisk/libgdata-gtasks,Pecisk/libgdata,pwithnall/libgdata,Distrotech/libgdata,Distrotech/libgdata,thiblahute/libgdata,Pecisk/libgdata,Distrotech/libgdata,thiblahute/libgdata,Pecisk/libgdata,Pecisk/libgdata-gtasks