Agent operators should be aware of ability to use multiple RPCs

[tkporter]

Instead of just relying upon a single RPC URL, agents can generally use multiple RPC URLs. We should make sure this is clear to operators, both validators and relayers (definitely care more about validators being aware of this atm as there are more validator operators)

The setup to describe is as follows:

EVM:

• configure multiple using https://docs.hyperlane.xyz/docs/operate/config-reference#chainschain_namecustomrpcurls (the little hint here saying this is EVM only is now stale)
• can customize single vs fallback vs quorum https://docs.hyperlane.xyz/docs/operate/config-reference#chainschain_namerpcconsensustype. Fallback == tries the first url, falls back to the next if needed, etc (prioritizes liveness). Quorum == requires a majority of the RPC URLs to agree with each other (prioritizes safety and allows some liveness redundancy). This is EVM only

Cosmos:

• configure multiple using https://docs.hyperlane.xyz/docs/operate/config-reference#chainschain_namecustomrpcurls
• In addition to RPC URLs, we also require you to configure gRPC URLs using customGrpcUrls, very similar to the customRpcUrls (I think this needs to be added to the docs?)
• no such thing as rpcConsensusType - just always fallback

SVM:

• configure multiple using https://docs.hyperlane.xyz/docs/operate/config-reference#chainschain_namecustomrpcurls, BUT only single is used. No fallback or anything yet