[TUTORIAL] Improve L2 Testnet Tutorial

[sbvegan]

Brief Description of the Docs Request

The, "Creating Your Own L2 Rollup Testnet" tutorial is currently pinned at an older branch so the tutorial doesn't break with the latest changes to develop. We should update it to be more recent.

Description of the Documentation You'd Like

Two approaches:

1. Update the tutorials/chain in the monorepo, verify the tutorial works as expected
2. Update the tutorial to be more evergreen. Explain that you need to deploy the contracts from op-contracts-vX.X.X, and run the client software from a different branch. Also check that the genesis and rollup config generation is solid.

Links to Related Pages

https://docs.optimism.io/builders/chain-operators/tutorials/create-l2-rollup

Additional Context

Feedback in this comment and thread from a chain operator: https://github.com/ethereum-optimism/superchain-registry/pull/125#issuecomment-2041415502 More feedback: https://github.com/ethereum-optimism/developers/discussions/329#discussioncomment-9016221