feat: add usage for nuxt3

[luoriwusheng-xia]

Proposed changes

Types of changes

What types of changes does your code introduce? Put an x in the boxes that apply

• [ ] Bugfix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [x] Documentation Update (if none of the other choices apply)

Linked Issues

Further comments

[vercel[bot]]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
postcss-px-conversion	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Aug 27, 2024 9:37am

[luoriwusheng-xia]

本来想把 Options导出， 发现会报错，不知道为啥 ； 在 nuxt3中，本来期望使用 import {Options} from 'postcss-px-conversion'

import {Options} from 'postcss-px-conversion'
// https://nuxt.com/docs/api/configuration/nuxt-config
export default defineNuxtConfig({
  postcss: {
    plugins: {
      'postcss-px-conversion': {
        unitType: 'px', // 要转化的单位
        viewportWidth: 375, // UI设计稿的宽度
        unitPrecision: 10, // 转换后的精度，即小数点位数
        viewportUnit: 'vw', // 指定需要转换成的视窗单位，默认vw
        minPixelValue: 1, // 默认值1，小于或等于1px则不进行转换
        includeFiles: [/\/pages\//], // 如果设置了include，那将只有匹配到的文件才会被转换
        excludeFiles: [/node_modules/, /pages\/active\/index\.vue/] // 设置忽略文件，用正则做目录名匹配
      } as Options
    }
  }
})

这样提供类型提示