Clarify the purpose of ibc-relayer-types crate compared to cosmos/ibc-rs

[Farhad-Shabani]

Summary

Developers who want to build their own relayer may be confused about which crate to use when it comes to importing IBC types. Remarkably, there is not enough context around the core purpose of the ibc-relayer-types crate.

Problem Definition

ibc-relayer-types and cosmos/ibc-rs crates have many common functionality and abstractions but with different roles. The role of ibc-relayer-types should be clearly presented from the client's perspective and be introduced as a toolkit for relayer development, with the latter focusing on on-chain operations. It became necessary when you look at it from developers' perspective, specifically those working on non-Cosmos chains. The ibc-relayer-types is the only crate they have to use among the Hermes crates. It’s needed since it enables them to interact with blockchains, while the others are mainly related to relaying logic and could be implemented by them internally.

Proposal

Though the reason behind having ibc-relayer-types and cosmos/ibc-rs crates in parallel can be found here, the purpose of each should be clearly explained in the Hermes root README and the README of ibc-relayer-types.Both mentioned repos use the same readme descriptions at the moment.

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