Update website for vite identifiers

[gkiely]

This section:
https://vanilla-extract.style/documentation/setup/#vite

Can be updated from:

Please note: There are currently no automatic readable class names during development. However, you can still manually provide a debug ID as the last argument to functions that generate scoped styles, e.g. export const className = style({ ... }, 'className');

To:

Please note: There are currently no automatic readable class names during development. However, you can still set identifiers by either:

• Manually providing a debug ID as the last argument to functions that generate scoped styles e.g. export const className = style({ ... }, 'className');

• Setting the identifiers property of the plugin in vite.config.ts:

import { defineConfig } from 'vite';
import { vanillaExtractPlugin } from '@vanilla-extract/vite-plugin';

export default defineConfig(({ command }) => ({
  vanillaExtractPlugin({
    identifiers: command === 'serve' ? 'debug' : 'short',
  }),
});