Re-define xwax as a DVS

The term "vinyl emulation software" is rather dated and whilst probably
more accurate, potential xwax users will be looking for a DVS.

README

@@ -5,7 +5,7 @@ xwax: Digital vinyl on Linux
 For installation instructions, see the INSTALL file. Instructions can
 be found in the xwax(1) man page and http://xwax.org/
 
-xwax is vinyl emulation software for Linux. It allows DJs and
+xwax is a digital vinyl system (DVS) for Linux. It allows DJs and
 turntablists to playback digital audio files (MP3, Ogg Vorbis, FLAC,
 AAC and more), controlled using a normal pair of turntables via
 timecoded vinyls.