MDL-39913 assign: Add help on filetype submissions

mod/assign/submission/file/lang/en/assignsubmission_file.php

@@ -24,6 +24,7 @@
 
 
 $string['acceptedfiletypes'] = 'Accepted file types';
+$string['acceptedfiletypes_help'] = 'Accepted file types can be restricted by entering a semicolon-separated list of mimetypes, for example \'video/mp4; audio/mp3; image/png; image/jpeg\'. You may also limit to extensions by including the dot, for example \'.png; .jpg\' If the field is left empty, then all file types are allowed.';
 $string['configmaxbytes'] = 'Maximum file size';
 $string['countfiles'] = '{$a} files';
 $string['default'] = 'Enabled by default';

mod/assign/submission/file/locallib.php

@@ -109,6 +109,7 @@ class assign_submission_file extends assign_submission_plugin {
 
         $name = get_string('acceptedfiletypes', 'assignsubmission_file');
         $mform->addElement('text', 'assignsubmission_file_filetypes', $name);
+        $mform->addHelpButton('assignsubmission_file_filetypes', 'acceptedfiletypes', 'assignsubmission_file');
         $mform->setType('assignsubmission_file_filetypes', PARAM_RAW);
         $mform->setDefault('assignsubmission_file_filetypes', $defaultfiletypes);
         $mform->disabledIf('assignsubmission_file_filetypes', 'assignsubmission_file_enabled', 'notchecked');