Create README2.md

[XiaoHai67890]

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Thank you for your contribution to OpenZeppelin Ethernaut. Before being able to integrate those changes, we would like you to sign our Contributor License Agreement.
You can sign the CLA by just posting a Pull Request Comment with the sentence below. Thanks.

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I confirm that I have read and hereby agree to the OpenZeppelin Contributor License Agreement

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_{You can retrigger this bot by commenting recheck in this Pull Request. Posted by the CLA Assistant Lite bot.}