[docs-infra] Add a feature list "component"

[danilo-leal]

• I have followed (at least) the PR section of the contributing guide.

Closes #41479
Preview: https://deploy-preview-41484--material-ui.netlify.app/experiments/docs/custom-components

<featureList>
-  Manages modal stacking when one-at-a-time just isn't enough.
-  Creates a backdrop, for disabling interaction below the modal.est
</featureList>

[mui-bot]

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https://deploy-preview-41484--material-ui.netlify.app/

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[alexfauquette]

I've implemented the option 3. I'm okay to go with this option too

[danilo-leal]

@alexfauquette yeah, me too! Thanks for doing it 🙏 I've deleted the other options and kept just that one. Good to go?

[alexfauquette]

Good for me, but I'm kind of the PR author for the markdown aspect 😅