Clarify runtime enable config behavior

[NathanNeurotic]

Summary

• clarify that runtime *_ENABLE keys only bring devices online after the initial config parse
• document that these keys cannot source the current boot’s CONFIG.INI and require a secondary load if overrides are needed

Testing

• Not run (documentation-only change)

---

Codex Task

[chatgpt-codex-connector]

You have reached your Codex usage limits for code reviews. You can see your limits in the Codex usage dashboard.
To continue using code reviews, you can upgrade your account or add credits to your account and enable them for code reviews in your settings.