Add missing translation.

plugin/bbb/lang/english.php

@@ -78,3 +78,5 @@ $strings['UpdateAllCourses'] = 'Update all courses';
 $strings['UpdateAllCourseSettings'] = 'Update all course settings';
 $strings['ThisWillUpdateAllSettingsInAllCourses'] = 'This will update at once all your course settings.';
 $strings['ThereIsNoVideoConferenceActive'] = 'There is no videoconference currently active';
+$strings['RoomClosed'] = 'Room closed';
+$strings['RoomClosedComment'] = ' ';