Update setups.md

[tagirb]

Re-phrase the scenario of forwarding to multiple upstreams, since the forward plugin supports multiple invocations in a single Server Block.

Thank you for contributing to CoreDNS' website!

Note:

• All text listed in /plugins is a copied from https://github.com/coredns/coredns/tree/master/plugin.

• The release notes are copied from https://github.com/coredns/coredns/tree/master/notes.

Any pull request that updates either of those should be directed to the CoreDNS repository: https://github.com/coredns/coredns .

[chrisohaver]

Thanks for updating this! LGTM.

Please sign the commits per the DCO.

[tagirb]

Done, thanks!