po: add a test translation of one string through zanata

po: add a test translation of one string through zanata

I use the web translation interface to translate one simple string,
then I clicked on the .po link. The file I get is called "systemd.po",
but I saved it over pt_BR.po. Then I had to do
    sed -i -r 's/\s+$//' po/pt_BR.po
    truncate --size=-1 po/pt_BR.po
(i.e. fix whitespace issues) and commit. So it seems zanata does not mess up
existing copyright marks and allows for proper attribution.