Add Tailwind CSS IntelliSense snippet to readme

[G3root]

tailwind vscode extension has a experimental support for autocompletion by custom regex,
add a working snippet to README

for reference https://github.com/joe-bell/cva#tailwind-css-intellisense

[alanonthegit]

@G3root this would be super useful if possible

[kndwin]

Would the below work?

{
  "tailwindCSS.experimental.classRegex": [
    ["styled\\(([^)]*)\\)", "[\"'`]([^\"'`]*).*?[\"'`]"]
  ]
}

I took this from stylemapper's docs since I believe the regex is pretty similiar