Adding a cross link (#13218)

Fixing a header and adding a crosslink to "create a new Flutter app".

Author: sfshaza2

src/content/tools/antigravity.md

@@ -24,7 +24,7 @@ and answer questions.
 Install the latest version of Antigravity for your platform by visiting
 the [Antigravity site](https://antigravity.google/download).
 
- 1. <h3>Open **Antigravity**</h3>
+ 1. <h3>Open Antigravity</h3>
 
     When opening Antigravity for the first time,
     a **How do you want to use Antigravity** screen displays and
@@ -78,8 +78,11 @@ the [Antigravity site](https://antigravity.google/download).
   1. For these tips and more that show some of Antigravity's benefits,
      watch the following 10-minute [Flutter + Antigravity video][ag-video]:
 
-  <YouTubeEmbed id="YY2w2JEX2xk"
-    title="Flutter + Antigravity in 10 minutes"></YouTubeEmbed>
+     <YouTubeEmbed id="YY2w2JEX2xk"
+       title="Flutter + Antigravity in 10 minutes"></YouTubeEmbed>
+
+For a walkthrough on creating a new Flutter app in Antigravity,
+visit [Create a new Flutter app][].
 
-[ag-codelab]: {{site.codelabs}}/getting-started-google-antigravity#0
 [ag-video]: {{site.youtube-site}}/watch?v=YY2w2JEX2xk&t=1s
+[Create a new Flutter app]: /reference/create-new-app#antigravity