[examples] Fix v5 clone example instructions

[oliviertassinari]

I tried to run those commands to test something on a new project but it didn't work.

[mui-bot]

Netlify deploy preview

https://deploy-preview-43755--material-ui.netlify.app/

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[oliviertassinari]

cc @alelthomas notification test 😄

[mnajdova]

Nice catch, I am adding the step to the major release guide (nice, you already did it :)).

[oliviertassinari]

@mnajdova Yeah, I reworked the major release guide to merge Core and X. There are some differences, but the best practices seems to be the same between Base UI, Material UI, Pigment CSS, MUI X. I saw stuff missing in each version. https://mui-org.notion.site/React-Major-version-release-process-0178410ef26941e6a4f333f80ded127a