You probably want something like...
Site A network = 10.1.1.0 /24 with remote vpn user network =10.10.1.0 /24
Site B network = 10.1.2.0 /24
If you have a cheap vpn router then you can do something like...
Site A network/VPN users = 10.1.1.0 /24
Site B network/VPN users = 10.1.2.0 /24
The only document I can think of is the administrator user name/password to the hardware, because technically it is just a virtual cable between two sites(not much to document).