chore: add addLink

Author: Simon he

src/addLink.ts

@@ -0,0 +1,8 @@
+import { createElement } from "./createElement"
+export function addLink(str: string) {
+  document.head.appendChild(createElement('link', {
+    rel: 'stylesheet',
+    href: str,
+    type: 'text/css'
+  }))
+}