chore: prepare release

example/lib/main.dart

@@ -86,7 +86,14 @@ class _MyHomePageState extends State<MyHomePage> {
       ),
       body: RichEditor(
         key: keyEditor,
-        value: '<p> init html val </p>',
+        value: '''
+        <h1>Heading 1</h1>
+<h2>Heading 2</h2>
+<h3>Heading 3</h3>
+<h4>Heading 4</h4>
+<h5>Heading 5</h5>
+<h6>Heading 6</h6>
+        ''',
         // You can return a Link (maybe you need to upload the image to your
         // storage before displaying in the editor or you can also use base64
         getImageUrl: (image) {