DOC: add note in README.md about winget install jupyterlab

[rootsmusic]

In README.md, a note should be added about that the version available (4.0.2-1) for winget is not the latest version. It's unpleasant to install via winget and be immediately informed on startup that the installed version should be uninstalled because there's a newer version.

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[JasonWeill]

The README is not the best place to provide info about packaged versions of JupyterLab. It would be better to address this by updating the packages in winget, as stated in #609, which has an open pull request #647. @mbektas and @krassowski had commented on #647 but the pull request hasn't been updated since then; let's move this forward via the existing issue and PR.