[palas]

Context

This is a followup of #1379. And a response to this review: #1379 (comment).

This PR replaces a comment in readCardanoGenesisConfig with a Haddock that explains the need for readCardanoGenesisConfig to produce a placeholder Dijkstra configuration even when it is not read from disk and is not used.

How to trust this PR

This PR only changes documentation. It is a matter of verifying whether what it said is true.

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. See Running tests for more details
• Self-reviewed the diff
• Changelog fragment added in .changes/

[Copilot]

🟢 Approval recommended

The documentation matches the implementation, with no behavioral changes or unresolved findings.

No open issues 🎉

What changed in this PR

Documents why readCardanoGenesisConfig supplies a placeholder Dijkstra genesis when experimental hard forks are disabled.

Changes:

• Replaces an inline comment with Haddock explaining the placeholder and hard-fork behavior.
• Adds a documentation changelog fragment; no runtime or API changes.

File	Description
cardano-api/​src/​Cardano/​Api/​LedgerState.hs	Documents Dijkstra placeholder behavior.
.changes/​20261021_205127_cardano-api_palas_read_cardano_genesis_config_haddock.yml	Records the documentation update.

_{Review effort: Balanced}