[docs] Update Example render for React v18

[nnnnoel]

Summary

Update Example render for React v18

ReactDOM.render is deprecated

How did you test this change?

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[sizebot]

Comparing: b8cfda1...5646bd8

Critical size changes

Includes critical production bundles, as well as any change greater than 2%:

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-stable/react-dom/cjs/react-dom.production.min.js	=	131.30 kB	131.30 kB	=	41.97 kB	41.97 kB
oss-experimental/react-dom/cjs/react-dom.production.min.js	=	136.36 kB	136.36 kB	=	43.42 kB	43.42 kB
facebook-www/ReactDOM-prod.classic.js	=	432.75 kB	432.75 kB	=	79.58 kB	79.58 kB
facebook-www/ReactDOM-prod.modern.js	=	417.75 kB	417.75 kB	=	77.21 kB	77.21 kB
facebook-www/ReactDOMForked-prod.classic.js	=	432.75 kB	432.75 kB	=	79.58 kB	79.58 kB

Significant size changes

Includes any change greater than 0.2%:

(No significant changes)

Generated by 🚫 dangerJS against 5646bd8