docs: add collapsible animation instructions

apps/www/src/content/docs/components/collapsible.md

@@ -10,11 +10,46 @@ primitive: https://www.radix-vue.com/components/collapsible.html
 
 ## Installation
 
- 
+
+<Steps>
+
+### Run the following command
+
 ```bash
 npx shadcn-vue@latest add collapsible
 ``` 
 
+### Update `tailwind.config.js`
+
+Add the following animations to your `tailwind.config.js` file:
+
+```js title="tailwind.config.js" {5-18}
+/** @type {import('tailwindcss').Config} */
+module.exports = {
+  theme: {
+    extend: {
+      keyframes: {
+        'collapsible-down': {
+          from: { height: 0 },
+          to: { height: 'var(--radix-collapsible-content-height)' },
+        },
+        'collapsible-up': {
+          from: { height: 'var(--radix-collapsible-content-height)' },
+          to: { height: 0 },
+        },
+      },
+      animation: {
+        'collapsible-down': 'collapsible-down 0.2s ease-in-out',
+        'collapsible-up': 'collapsible-up 0.2s ease-in-out',
+      },
+    },
+  },
+}
+```
+  
+</Steps>
+
+
 ## Usage
 
 ```vue