docs: document `autoInit`

[dargmuesli]

Describe the feature

I've been wondering if there is a way to turn off eslint.config.js generation and only found the option when looking at the source code. I think it should be documented.

Additional information

• Would you be willing to help implement this feature?
• Could this feature be implemented as a module?

Final checks

• Read the contribution guide.
• Check existing discussions and issues.

[antfu]

Would you like to send a quick PR? Thanks

[dargmuesli]

Sure! Done ✅