Update docs to include references to CometBFT

[mmulji-ic]

Summary

With Gaia release v9.0.3, Gaia will use CometBFT instead of informalsystem/tendermint. The docs and branding need to be updated to reflect this.

Proposal

The following items need to be updated:

Tasks

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[adizere]

Hey folks, let us when you kick off work on this (noticed there's a branch, but no PR yet). Comet team would be glad to help review! CC @alijnmerchant21 .