Comment 1 for bug 1541192

The networking guide currently lacks information regarding DNS resolution for instances, so I think we should create a config-dns-resolution.rst file and populate it with the following methods:

1) To enable DNS resolution for instances on all neutron networks using the same one or more DNS resolvers, edit the dhcp_agent.ini file and set the dnsmasq_dns_servers option accordingly.

2) To enable DNS resolution for instances all neutron networks using DNS resolvers on the host (in /etc/resolv.conf) running the DHCP agent, edit the dhcp_agent.ini file and enable the dnsmasq_local_resolv option. Use with caution as this method can potentially leak internal DNS records.

3) To enable DNS resolution for instances on on individual networks, use the --dns-nameserver option with the neutron subnet-create command.

Add the file to the TOC in config.rst and I'll also reference it in the deployment scenarios.