添加一个介绍，并如何使用的demo

MeshDemo/assets/Script/Helloworld.ts

@@ -0,0 +1,16 @@
+const {ccclass, property} = cc._decorator;
+
+@ccclass
+export default class Helloworld extends cc.Component {
+
+    @property(cc.Label)
+    label: cc.Label = null;
+
+    @property
+    text: string = 'hello';
+
+    start () {
+        // init logic
+        this.label.string = this.text;
+    }
+}

MeshDemo/assets/Script/Helloworld.ts.meta

@@ -0,0 +1,9 @@
+{
+  "ver": "1.0.8",
+  "uuid": "e1b90feb-a217-4493-849d-9a611900d683",
+  "isPlugin": false,
+  "loadPluginInWeb": true,
+  "loadPluginInNative": true,
+  "loadPluginInEditor": false,
+  "subMetas": {}
+}