Fix PATH locations used in documentation

The current setting was based on Arch Linux, on which this script was developed. More restrictive versions of OpenVPN settings have ment this is becoming an error. Documentation updated.

Author: Jonathan Wright

README.md

@@ -48,7 +48,7 @@ before the device is closed:
 
 ```
 script-security 2
-setenv PATH /usr/bin:/bin
+setenv PATH /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
 up /etc/openvpn/update-systemd-resolved
 down /etc/openvpn/update-systemd-resolved
 down-pre