Update preconfigured_peers comment with IP example

[zhyatt]

The previous .json type config files had the following default setup which included an example of a non-domain based entry:

"preconfigured_peers": [ // List of defaults peers to connect on boot
            "peering.nano.org",
            "::ffff:138.201.94.249"
        ]

Currently we rely on comments in the example/generated .toml file for hints and although it mentions IP addresses, it seems like IPv6 is required and that isn't mentioned. It currently shows:

# A list of "address" (hostname or ip address) entries to identify preconfigured peers.
#preconfigured_peers = ["peering.nano.org"]

This should be clarified further in the comment/hints of the generated .toml files.