docs:add global api

docs/.vitepress/config.ts

@@ -49,6 +49,12 @@ export default defineConfig({
           { text: '内部右键菜单', link: '/guide/contextmenu-internal' },
           { text: '自定义右键菜单', link: '/guide/contextmenu-custom' }
         ]
+      },
+      {
+        text: 'API',
+        items: [
+          { text: '全局API', link: '/guide/api' }
+        ]
       }
     ],
     socialLinks: [{

docs/guide/api.md

@@ -0,0 +1,21 @@
+# 全局API
+
+## 使用方式
+
+```javascript
+import Editor from "@hufe921/canvas-editor"
+
+const instance = new Editor(container, <IElement[]>data, options)
+instance.apiName()
+```
+## destroy
+功能：销毁编辑器
+
+用法：
+```javascript
+instance.destroy()
+```
+
+::: warning
+仅销毁编辑器dom及相关事件，菜单栏、工具栏、外部变量等需自行处理。
+:::