Modify to standard long option (for versions after 0.9.1) (#14)

-c
--config

XrayR.service

@@ -12,7 +12,7 @@ LimitRSS=infinity
 LimitCORE=infinity
 LimitNOFILE=999999
 WorkingDirectory=/usr/local/XrayR/
-ExecStart=/usr/local/XrayR/XrayR -config /etc/XrayR/config.yml
+ExecStart=/usr/local/XrayR/XrayR --config /etc/XrayR/config.yml
 Restart=on-failure
 RestartSec=10