[docs] Put pnpm install commands as the second one

[ahmadnadeem6236]

Fixes : #42699

• [x] material-ui/getting-started/installation/
• [x] base-ui/getting-started/quickstart/
• [x] joy-ui/getting-started/installation/
• [x] system/getting-started/installation/

https://github.com/mui/material-ui/assets/87973871/c7878423-42a4-4856-8034-aa06d5b50b31

[mui-bot]

Netlify deploy preview

• docs/data/base/getting-started/quickstart/quickstart.md
• docs/data/joy/customization/right-to-left/right-to-left.md
• docs/data/joy/getting-started/installation/installation.md
• docs/data/material/components/about-the-lab/about-the-lab.md
• docs/data/material/components/icons/icons.md

Bundle size report

No bundle size changes (Toolpad) No bundle size changes

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