This PR adds a bit more information when running the upgrade tool to
know what version of Tailwind CSS you're upgrading from. This will help
users and maintainers when things go wrong.
Will have another PR up soon that errors when the Tailwind CSS version
in package.json and node_modules don't match.
### Test plan
Ran this one one of our older projects and saw the version logged
correctly.
<img width="1055" height="363" alt="image"
src="https://github.com/user-attachments/assets/5cbf4c52-ea0f-42c8-bd55-5bae2ed511de"
/>
Closes https://github.com/tailwindlabs/tailwindcss.com/issues/2061
In lieu of finding a place to put this on the docs we can at least
document this in the readme for the plugin.
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Co-authored-by: Philipp Spiess <hello@philippspiess.com>
