Change the DNS servers on an ESXi host

This can be done without disruption.

1. SSH into the ESXi host
2. Get existing DNS servers: esxcli network ip dns server list
3. Add a new DNS server: esxcli network ip dns server add --server=10.0.0.7
4. Remove an existing DNSserver: esxcli network ip dns server remove --server=10.0.0.8