add help text for available for students setting.

lang/en/attendance.php

@@ -382,5 +382,8 @@ $string['defaultsessionsettings'] = 'Default session settings';
 $string['defaultsessionsettings_help'] = 'These settings define the defaults for all new sessions';
 
 $string['studentavailability'] = 'Available for students (minutes)';
+$string['studentavailability_help'] = 'When students are marking their own attendance, the number of minutes after session starts that this status is available.
+ <br/>If empty, this status will always be available, If set to 0 it will always be hidden to students.';
+
 $string['somedisabledstatus'] = '(Some options have been removed as the session has started.)';
 $string['invalidstatus'] = 'You have selected an invalid status, please try again';

renderer.php

@@ -1633,7 +1633,9 @@ class mod_attendance_renderer extends plugin_renderer_base {
                              get_string('points', 'attendance'));
         $table->align = array('center', 'center', 'center', 'center', 'center', 'center');
         if ($studentscanmark) {
-            $table->head[] = get_string('studentavailability', 'attendance');
+            $table->head[] = get_string('studentavailability', 'attendance').
+                $this->output->help_icon('studentavailability', 'attendance');
+
             $table->align[] = 'center';
         }
         $table->head[] = get_string('action');