docs: faq: How do I edit `openvpn.conf`?
docs: faq: How do I edit `openvpn.conf`?

* It gets asked too many times.

dx9/docker-openvpn,wernerb/docker-openvpn,slamont/docker-openvpn,jvassev/docker-openvpn,elie195/docker-openvpn,StefanGuelland/docker-openvpn,kylemanna/docker-openvpn,richnologies/docker-openvpn,gl-sergei/docker-openvpn,mouyigang/docker-openvpn,myplacedk/docker-openvpn,shanonvl/docker-openvpn,csakoda/docker-openvpn,hjnijlunsing/docker-openvpn-armhf,alessandro-aglietti/docker-openvpn,rdev02/docker-openvpn,caervs/docker-openvpn,morcavon/docker-openvpn,jeffcao/docker-openvpn