fix: 优化复制代码格式化 (#941)

src/sites/doc/components/demo-block/basedUtil.ts

@@ -18,7 +18,7 @@ export function decompressText(str: string): any {
 }
 
 export function copyCodeHtml(code: string, callback: any): void {
-  const oInput = document.createElement('input');
+  const oInput = document.createElement('textarea');
   oInput.value = code;
   document.body.appendChild(oInput);
   oInput.select(); // 选择对象