docs(plugin-iconify): update doc

packages/plugin-iconify/README.md

@@ -1,5 +1,7 @@
 # `@vuepress-plume/vuepress-plugin-iconify`
 
+添加 `iconify` 图标库支持。并注入全局组件 `<Iconify>`
+
 ## Install
 ```
 yarn add @vuepress-plume/vuepress-plugin-iconify
@@ -16,3 +18,23 @@ module.exports = {
   // ...
 }
 ```
+
+## Options
+
+```ts
+interface IconifyOptions {
+  /**
+   * 组件名， 默认 `Iconify`
+   */
+  componentName?: string
+  color?: string
+  size?: string | number
+}
+
+```
+
+## Component
+
+```vue
+<Iconify name="material-symbols:home" color="currentColor" size="1em" />
+```