[docs] Change pnpm order, place second

[oliviertassinari]

Summary

pnpm grew to be the second most used dependency management tool: https://2023.stateofjs.com/en-US/libraries/monorepo_tools/ (after npm)

So I believe we should change the order on all the pages of the docs, e.g. https://mui.com/material-ui/getting-started/installation/, https://mui.com/x/react-data-grid/getting-started/#installation.

I explored a bit this topic in https://x.com/olivtassinari/status/1789065680370737630.

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• Update Material UI docs [docs] Update pnpm order, move to second material-ui#42712
• Update MUI X docs [docs] Bump pnpm priority as a package manager mui-x#13894
• Update Base UI docs
• Update Pigment CSS docs
• Update Toolpad docs

[oliviertassinari]

@alelthomas maybe a small one, to help discover the codebase and process. This would typically be left to the community otherwise.

[rotem227]

@oliviertassinari - this issue is still tagged as "ready to take" so I've created a PR for it.
Should I close it or is it still relevant?

[oliviertassinari]

Should I close it or is it still relevant?

@rotem227 We have an open PR for it mui/material-ui#42712. I think it's about pushing a couple of commits on this PR to get it to the finish line.

[oliviertassinari]

I'm reopening and moving this to mui-public. At this stage, it's a cross MUI docs initiative, cc @samuelsycamore for awareness.