docs: update readme to reflect vite's deprecation of globEager

[rockwellll]

From https://github.com/ElMassimo/stimulus-vite-helpers/pull/12#issue-2048150674,

The globEager function was deprecated as of Vite 3.0 and has been removed in Vite 5.0. This updates the README to use the suggested glob function with an eager argument instead.

https://vitejs.dev/guide/migration#removed-deprecated-apis vitejs/vite#14118

I noticed that the plugins page was missing that, I was in the process of upgrading vite-ruby and had some hard time because the docs was not being reflected.

Hope this helps others out.

Thanks for this amazing project!

[ElMassimo]

Thanks Ahmed!