feat: rewrite to use app config and rework docs (#143)

Co-authored-by: Daniel Roe <daniel@roe.dev>
Co-authored-by: Sébastien Chopin <seb@nuxt.com>

build.config.ts

@@ -1,12 +0,0 @@
-import fs from 'node:fs/promises'
-import { join, resolve } from 'node:path'
-import { defineBuildConfig } from 'unbuild'
-
-export default defineBuildConfig({
-  hooks: {
-    'rollup:done': async (ctx) => {
-      // copy env.d.ts to dist
-      await fs.copyFile(resolve('src/env.d.ts'), join(ctx.options.outDir, 'env.d.ts'))
-    }
-  }
-})