chore: update tailwind to v3 and update the readme (#2209)

using `.cjs` for file extensions

chore: update tailwind to v3 and update the readme

docs/src/pages/guides/styling.md

@@ -211,8 +211,7 @@ And create 2 files in your project root: `tailwind.config.cjs` and `postcss.conf
 ```js
 // tailwind.config.cjs
 module.exports = {
-  mode: 'jit',
-  purge: ['./public/**/*.html', './src/**/*.{astro,js,jsx,svelte,ts,tsx,vue}'],
+  content: ['./public/**/*.html', './src/**/*.{astro,js,jsx,svelte,ts,tsx,vue}'],
   // more options here
 };
 ```

examples/with-tailwindcss/package.json

@@ -11,6 +11,6 @@
   "devDependencies": {
     "astro": "^0.21.12",
     "autoprefixer": "^10.4.0",
-    "tailwindcss": "^2.2.19"
+    "tailwindcss": "^3.0.5"
   }
 }

examples/with-tailwindcss/tailwind.config.js

@@ -1,4 +1,3 @@
 module.exports = {
-  mode: 'jit',
-  purge: ['./src/**/*.{astro,html,js,jsx,svelte,ts,tsx,vue}'],
+  content: ['./src/**/*.{astro,html,js,jsx,svelte,ts,tsx,vue}'],
 };