Write a tutorial showing how to build a custom ledger for Hydra

[noonio]

• Show which repos to fork
• Roughly the code changes required
• How you can test it

It doesn't need to be super-reproducible; it can point to the old PRs; but it should be enough to get someone started if they are motivated.

[locallycompact]

I don't think this is something we particularly want to recommend people do. Extending plutus is fragile, especially when it still informs the L1 toolchain, and we don't know the ways in which we can safely override the ledger code itself.

A better way to do this could be to maintain an L2 ledger ourselves, that extends cardano-ledger compositionally. then it's natural and safe for someone to fork that and extend it.

[noonio]

It's an interesting idea, and a good point.

I think the problem I have is I don't want us to take on extra work of maintaining a separate ledger; and certainly not indefinitely.

I think what I'd like is just a middle-ground between that, and what we've done so far, and having a full implementation. I more want to write a kind of experience-report-ish style document, that captures the knowledge we have gained. At a minimum it could just be some entries on the Logbook.

I.e. I don't think the tutorial needs to be super-followable; just give a guide should someone wish to do it in the future.