[Docs] Add all CSS Variables

[r-priyam]

Is your feature request related to a problem? Please describe.
To add all the CSS variables used in generating the static site

Additional context
CSS variables like - https://v2.vuepress.vuejs.org/reference/default-theme/styles.html#palette-file

[ElMassimo]

@r-priyam Unlike Vitepress and Vuepress, îles does not provide a default theme.

You have full control on which CSS you import (from Vue components, or from src/app.ts).

Once the APIs have stabilized, I will document how to create plugins and themes for îles. I will also consider creating an official @islands/docs preset to create documentation sites (although Vitepress is already a good option for that).

[r-priyam]

Aye Aye, Got it. I would love to see more of this because I guess there are so many features around. Loved iles, Thank you for the fast response.