Improve use of triggered string. is really first notified.

lang/en/attendance.php

@@ -444,7 +444,7 @@ $string['thiscourse'] = 'This course';
 $string['time'] = 'Time';
 $string['timeahead'] = 'Multiple sessions that exceed one year cannot be created, please adjust the start and end dates.';
 $string['to'] = 'to:';
-$string['triggered'] = 'First triggered';
+$string['triggered'] = 'First notified';
 $string['tuseremail'] = 'Email';
 $string['tusername'] = 'Full name';
 $string['unknowngroup'] = 'Unknown group';