docs: update usage

README.md

@@ -47,12 +47,12 @@ Add it to `vite.config.ts`
 
 ```ts
 // vite.config.ts
-import Banner from 'vite-plugin-banner'
+import banner from 'vite-plugin-banner'
 // Other dependencies...
 
 export default defineConfig({
   plugins: [
-    Banner('This is the Banner content.'),
+    banner('This is the banner content.'),
   ]
 })
 ```
@@ -62,7 +62,7 @@ When you run `npm run build` on your project, In the `dist` folder(Or the [build
 e.g. in `app.b3a7772e.js`:
 
 ```js
-/* This is the Banner content. */
+/* This is the banner content. */
 var e=Object.assign;import{M as t,d as a,u as r,c......
 ```
 
@@ -91,7 +91,7 @@ import pkg from './package.json'
 
 export default defineConfig({
   plugins: [
-    Banner(`/**\n * name: ${pkg.name}\n * version: v${pkg.version}\n * description: ${pkg.description}\n * author: ${pkg.author}\n * homepage: ${pkg.homepage}\n */`),
+    banner(`/**\n * name: ${pkg.name}\n * version: v${pkg.version}\n * description: ${pkg.description}\n * author: ${pkg.author}\n * homepage: ${pkg.homepage}\n */`),
   ]
 })
 ```
@@ -125,7 +125,7 @@ Such as:
 // vite.config.ts
 export default defineConfig({
   plugins: [
-    Banner(`
+    banner(`
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@@ -157,6 +157,38 @@ var e=Object.assign;import{M as t,d as a,u as r,c......
 
 ### Optional parameter format
 
+I'm not sure what other scenarios besides VitePress need to use this method to pass in options, so I use VitePress as an example, I hope it can give you a reference
+
+```ts
+// docs/.vitepress/config.ts
+import { defineConfig } from 'vitepress'
+import banner from 'vite-plugin-banner'
+import pkg from '../../package.json'
+
+const outDir = '../dist'
+
+export default defineConfig({
+  // Specify the output directory for packaging
+  outDir,
+
+  // Use Vite plugins
+  vite: {
+    plugins: [
+      // Please remember to use the options in Object format here
+      banner({
+        outDir,
+        content: `/**\n * name: ${pkg.name}\n * version: v${pkg.version}\n * description: ${pkg.description}\n * author: ${pkg.author}\n * homepage: ${pkg.homepage}\n */`,
+      }),
+    ],
+  },
+  // ...
+})
+```
+
+Why do it?
+
+Because in VitePress, what you get through `viteConfig.build.outDir` is always a `.temp` temporary directory, not the final output directory, so you need to manually specify the output directory to inform the plugin
+
 ## License
 
 MIT License © 2021 [chengpeiquan](https://github.com/chengpeiquan)