add pld template

template for http://pld-linux.org linux distribution

altho pld maintains [the template](https://github.com/pld-linux/gem2rpm/blob/master/pld.spec.erb) in it's [own repo](https://github.com/pld-linux/gem2rpm), maybe it's useful to keep one in upstream as well. for example cases when you make change that affects all templates.