Fixes for Bug 3089, Date entry fields should indicate required date format

[koha_fer] / koha-tmpl / intranet-tmpl / prog / en / includes / date-format.inc

<!-- TMPL_IF NAME="dateformat_us" -->(MM/DD/YYYY)<!-- TMPL_ELSIF NAME="dateformat_metric" -->(DD/MM/YYYY)<!-- TMPL_ELSE -->(YYYY/MM/DD)<!-- /TMPL_IF -->