Update config to use `allowPublishToZeroTopicPeers`

[James Schinner]

Sample readme config shows the user of allowPublishToZeroPeers when I think I should be allowPublishToZeroTopicPeers?

[Syed]

yes

[Hayden Young]

#1178

We have updated the documentation to use the latest GossipSub but anyone using an older version (of GossipSub) should be aware that allowPublishToZeroPeers to allowPublishToZeroTopicPeers is a breaking change.

Please refer to the breaking changes and release notes for more information.