Extend list of allowed uploads with Open Document format (oasis, such as LibreOffice, OpenOffice) to
,application/vnd.oasis.opendocument.text,application/vnd.oasis.opendocument.spreadsheet,application/vnd.oasis.opendocument.presentation

Here is the code line:
/rocketchat-file-upload/server/startup/settings.js#L12