Update Readme with a brief description about this repository and why it is needed

[ggedde]

I am assuming this plugin just allows Vue to work with Vite, but it is not clear. I would have thought that Vue works with Vite out of the box. It might seem implied to most that this is required if you are using Vite with Vue, but I am not sure.
Is it required for all versions on Vite and Vue or just earlier versions?
And what does this plugin actually do? I can look at the documentation and get a rough idea, but it would be nice to have an overview on the Readme file.
Thanks