Add flat config preset for compiled & fix docs

[AllySummers]

What is this change?

This PR:

• Adds a flat config preset for the ESLint plugin
• Corrects the readme for the eslint plugin to match the actual code

Why are we making this change?

• So that people using @compiled/eslint-plugin can use this with flat config without the legacy compat utils
• To make our documentation more accurate

PR checklist

Don't delete me!

I have...

• [x] Updated or added applicable tests
• [x] Updated the documentation in website/

Closes #1691

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: 4cdfe7f4a42229fcf18f9ea13642a3a6e4516dc5

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@compiled/eslint-plugin	Minor

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