add basic new chaining

docs/src/demos/Examples/Simple/index.vue

@@ -1,5 +1,11 @@
 <template>
-  <editor-content :editor="editor" />
+  <div>
+    <button @click="() => console.log(editor.focus())">focus</button>
+    <button @click="() => console.log(editor.insertText('hello'))">insert</button>
+    <button @click="editor.chain().focus().insertText('wat').insertHTML('<p>2</p>').run()">chain</button>
+    <button @click="editor.chain().insertText('1').focus().run()">chain</button>
+    <editor-content :editor="editor" />
+  </div>
 </template>
 
 <script>
@@ -16,6 +22,7 @@ export default {
   data() {
     return {
       editor: null,
+      console: console,
     }
   },