Have appropriate diagrams in the docs

[nambrot]

Our diagrams need an overhaul. This is two parts:

1. We need the source of truth kinda diagrams. These should be done in mermaid for versioning. imo we need the following:

   • A basic message passing diagram (showing mailboxes and ISMs, without going to detail about how security works) I.e. on https://docs.hyperlane.xyz/docs/protocol/overview or https://docs.hyperlane.xyz/docs/protocol/messaging
   • also diagrams about PI and the deployment of ISMs (v confusing unless you are us)
   • A diagram about how warp routes can set security. It can hide the security details away by linking to the above page/diagram

2. For those diagrams, then making more approachable, visually appealing versions of those for blog posts, twitter, etc.

[anettrolikova]

Warp Route simple flow:

[yorhodes]

relevant https://github.com/hyperlane-xyz/hyperlane-token/pull/41

[anettrolikova]

This issue is closed but I think we should get better at diagrams in docs. May create new issue on this