http://web.archive.org/web/20170710045637/https://opendatakit.org/help/form-design/data-preloading has all the old content. I've added an issue at https://github.com/XLSForm/xlsform.github.io/issues/166 so we can add the options to the docs.
I think the reason it's not added is because we had been discussing deprecating search() and wanted to limit the number of people currently using it.