Add docs for auth and rate limiting

[abidlabs]

Adds some docs that are useful for auth and rate limiting.

For rate limiting, I think it's better just to provide an example of how to use Gradio's existing primitives instead of creating a new shallow abstraction, closes: #2517

The auth docs are motivated by this internal thread

[gradio-pr-bot]

🪼 branch checks and previews

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Install Gradio from this PR

pip install https://gradio-pypi-previews.s3.amazonaws.com/f504b525375143a0100fae692c553778e7cd1db2/gradio-5.43.1-py3-none-any.whl

Install Gradio Python Client from this PR

pip install "gradio-client @ git+https://github.com/gradio-app/gradio@f504b525375143a0100fae692c553778e7cd1db2#subdirectory=client/python"

Install Gradio JS Client from this PR

npm install https://gradio-npm-previews.s3.amazonaws.com/f504b525375143a0100fae692c553778e7cd1db2/gradio-client-1.17.1.tgz

Use Lite from this PR

<script type="module" src="https://gradio-lite-previews.s3.amazonaws.com/f504b525375143a0100fae692c553778e7cd1db2/dist/lite.js""></script>

[gradio-pr-bot]

🦄 change detected

This Pull Request includes changes to the following packages.

Package	Version
gradio	patch

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• Add docs for auth and rate limiting

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[aliabd]

Left a minor comment but docs look good and the demo works great!

[abidlabs]

Thanks so much @aliabd!