MDL-29795 assign: Add missing inactiveoverridehelp lang string

mod/assign/lang/en/assign.php

@@ -258,6 +258,7 @@
 $string['groupsnone'] = 'There are no groups in this course';
 $string['hideshow'] = 'Hide/Show';
 $string['hiddenuser'] = 'Participant ';
+$string['inactiveoverridehelp'] = '* Student does not have the correct group or role to attempt the assignment';
 $string['instructionfiles'] = 'Instruction files';
 $string['introattachments'] = 'Additional files';
 $string['introattachments_help'] = 'Additional files for use in the assignment, such as answer templates, may be added. Download links for the files will then be displayed on the assignment page under the description.';