add systemd unit for refresher and document it

README.md

@@ -98,6 +98,8 @@ exec awesome
 Since the MSMFB_SW_REFRESHER does not seem to be working i wrote this instead.
 Just compile and put in you ~/ or whereever so xinit can run it.
 
+You can also use the included systemd unit file for the refresher.
+
 ## Enabling ADB and RNDIS (reverse USB tethering)
 1: Create this link for ADB to be able to find the shell, etc.
   ln -s / /system

system/refresher.service

@@ -0,0 +1,10 @@
+[Unit]
+Before=graphical.target
+
+[Service]
+Type=simple
+ExecStart=/bin/refresher
+
+[Install]
+WantedBy=multi-user.target
+