feat:补充readme

README.md

@@ -2,4 +2,12 @@
 npm install
 npm start
 
+ <div id="app"></div>
+<script src="./bundle.js"></script>
+<script>
+    new MdEditor({
+    el: "#app"
+    });
+</script>
+
 ```
\ No newline at end of file