feat: add override internal function api #260

docs/guide/override.md

@@ -0,0 +1,20 @@
+# 重写方法
+
+## 使用方式
+
+```javascript
+import Editor from "@hufe921/canvas-editor"
+
+const instance = new Editor(container, <IElement[]>data, options)
+instance.override.overrideFunction = ()=>{}
+```
+
+## paste
+
+功能：重写粘贴方法
+
+用法：
+
+```javascript
+instance.override.paste = (evt: ClipboardEvent) => void
+```