sesman: Update Xorg help comment for Arch Linux
As reported in Arch Linux looks to me like using Xorg wrapper now.
@@ -65,7 +65,7 @@ SyslogLevel=DEBUG
; Fedora 26 or later : param=/usr/libexec/Xorg
; Debian 9 or later : param=/usr/lib/xorg/Xorg
; Ubuntu 16.04 or later : param=/usr/lib/xorg/Xorg
-; Arch Linux : param=/usr/bin/Xorg or param=Xorg
+; Arch Linux : param=/usr/lib/xorg-server/Xorg
; CentOS 7 : param=/usr/bin/Xorg or param=Xorg
;
param=Xorg
