added installation instructions for archlinux
added installation instructions for archlinux

ap--/python-seabreeze,craighiller/python-seabreeze,ap--/python-seabreeze,TobiasNils/python-seabreeze,TobiasNils/python-seabreeze,ap--/python-seabreeze,TobiasNils/python-seabreeze,craighiller/python-seabreeze