Updated: serienbrief 0.2.2-r1

I just released a little update for serienbrief. It only adds a README file with build and dependency information for users using a distribution without an official serienbrief package (perhaps each and every distribution except Gentoo Linux). Therefore, no new version number, just an -r1 added.
Nobody has to update to this version if 0.2.2 is being installed, as this really only is a documentation update.