Update README.md and fix a typo (#1645)

* Add section on README about the recommended Node.js version.

* fix typo in the tutorial

* Update README and package.json

Update them according to the result

Author: StephenChips

README.md

@@ -11,6 +11,9 @@ pnpm i
 pnpm run dev
 ```
 
+This project requires Node.js to be `v14.0.0` or higher, because we use new JavaScript features in our code, such as optional chaining.
+
+
 ## Working on the content
 
 - See VitePress docs on supported [Markdown Extensions](https://vitepress.vuejs.org/guide/markdown.html) and the ability to [use Vue syntax inside markdown](https://vitepress.vuejs.org/guide/using-vue.html).

package.json

@@ -1,4 +1,7 @@
 {
+  "engines": {
+    "node": ">=14.0.0"
+  },
   "scripts": {
     "dev": "vitepress",
     "build": "vitepress build",

src/tutorial/src/step-11/description.md

@@ -45,7 +45,7 @@ Then, we can use the component in the template as:
 <div class="html">
 
 ```js
-import ChildComp from './ChildComp.vue'
+import ChildComp from './ChildComp.js'
 
 createApp({
   components: {