Merge pull request hashicorp#2033 from alex1x/master

resource/vpc_dhcp_options: Updated documentation about how to maintain default AWS DNS servers

website/docs/r/vpc_dhcp_options.html.markdown

@@ -41,7 +41,7 @@ resource "aws_vpc_dhcp_options" "foo" {
 The following arguments are supported:
 
 * `domain_name` - (Optional) the suffix domain name to use by default when resolving non Fully Qualified Domain Names. In other words, this is what ends up being the `search` value in the `/etc/resolv.conf` file.
-* `domain_name_servers` - (Optional) List of name servers to configure in `/etc/resolv.conf`.
+* `domain_name_servers` - (Optional) List of name servers to configure in `/etc/resolv.conf`. If you want to use the default AWS nameservers you should set this to `AmazonProvidedDNS`.
 * `ntp_servers` - (Optional) List of NTP servers to configure.
 * `netbios_name_servers` - (Optional) List of NETBIOS name servers.
 * `netbios_node_type` - (Optional) The NetBIOS node type (1, 2, 4, or 8). AWS recommends to specify 2 since broadcast and multicast are not supported in their network. For more information about these node types, see [RFC 2132](http://www.ietf.org/rfc/rfc2132.txt).
@@ -52,6 +52,7 @@ The following arguments are supported:
 * `domain_name_servers`, `netbios_name_servers`, `ntp_servers` are limited by AWS to maximum four servers only.
 * To actually use the DHCP Options Set you need to associate it to a VPC using [`aws_vpc_dhcp_options_association`](/docs/providers/aws/r/vpc_dhcp_options_association.html).
 * If you delete a DHCP Options Set, all VPCs using it will be associated to AWS's `default` DHCP Option Set.
+* In most cases unless you're configuring your own DNS you'll want to set `domain_name_servers` to `AmazonProvidedDNS`. 
 
 ## Attributes Reference