add notes for tailwind3/4 compatibility

[SteffenDE]

No description provided.

[SteffenDE]

Should we add a note that current v4 releases (at the time of writing up to 4.0.3) don't bundle the first party JS dependencies?

Something like

5.  At the time of writing, the most recent Tailwind version 4.0.3 does not bundle first party JavaScript plugins.
    The Phoenix generators rely on those for plugins.
    Therefore, you may need to `npm install tailwindcss @tailwindcss/forms --save-dev` until the [upstream issue](https://github.com/tailwindlabs/tailwindcss/pull/15934) is fixed.

[josevalim]

Should we add a note that current v4 releases (at the time of writing up to 4.0.3) don't bundle the first party JS dependencies?

I would not release a new version until Tailwind is fixed, so it is not strictly required. Anyway is fine though!

[SteffenDE]

Perfect, thank you! 🙌🏻