Update documentation to refer to CometBFT

[julienrbrt]

Update SDK documentation (all *.md files) to refer to CometBFT (only when about Tendermint Core and not Tendermint algorithm).

IMHO only main/v0.48+ should have all the renaming changes in the docs, as in anything up to v0.47, Tendermint Core = CometBFT, so renaming would be pointless (and time costly too).

[cipherzzz]

@julienrbrt - I can do this if you want

[julienrbrt]

@julienrbrt - I can do this if you want

That would be awesome! Thank you!
I'll be happy to review it.