Changed IPv6 pool documentation in accel-ppp services
to named IPv6 pools.
https://vyos.dev/T5865
(cherry picked from commit f5b79621d0c841ee9a596543a05ad1acc9130c1d)
The command path:
set vpn sstp ssl key-file <file>
Does not appear to exist anymore, as per https://github.com/vyos/vyos-1x/pull/1038
Can the doc be updated with instructions on SSTP setup with new command structure?