Small fix to guide styling

[aliabd]

tiny fix that's been annoying me for a while. On guides without headings, there's no need to show a headings section under the guide name in the sidebar.

vs

[gradio-pr-bot]

🪼 branch checks and previews

•	Name	Status	URL
	Spaces	ready!	Spaces preview
	Website	ready!	Website preview
	Storybook	ready!	Storybook preview
🦄	Changes	detecting...

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Install Gradio from this PR

pip install https://gradio-builds.s3.amazonaws.com/bc4949720a31ebb99fb9504e762440eb95122266/gradio-4.36.1-py3-none-any.whl

Install Gradio Python Client from this PR

pip install "gradio-client @ git+https://github.com/gradio-app/gradio@bc4949720a31ebb99fb9504e762440eb95122266#subdirectory=client/python"

Install Gradio JS Client from this PR

npm install https://gradio-builds.s3.amazonaws.com/bc4949720a31ebb99fb9504e762440eb95122266/gradio-client-1.1.1.tgz

[gradio-pr-bot]

🦄 change detected

This Pull Request includes changes to the following packages.

Package	Version
website	minor

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With the following changelog entry.

Small fix to guide styling

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[freddyaboulton]

Nice @aliabd !