lang/portfolio MDL-20897 Add missing lang strings

For new portfolio formats

lang/en_utf8/portfolio.php

@@ -44,9 +44,13 @@ $string['failedtosendpackage'] = 'Failed to send your data to the selected portf
 $string['failedtopackage'] = 'Could not find files to package';
 $string['filedenied'] = 'Access denied to this file';
 $string['filenotfound'] = 'File not found';
+$string['format_document'] = 'Document';
 $string['format_file'] = 'File';
 $string['format_richhtml'] = 'HTML with attachments';
+$string['format_pdf'] = 'PDF';
 $string['format_plainhtml'] = 'HTML';
+$string['format_presentation'] = 'Presentation';
+$string['format_spreadsheet'] = 'Spreadsheet';
 $string['format_image'] = 'Image';
 $string['format_mbkp'] = 'Moodle Backup Format';
 $string['format_video'] = 'Video';