style(web-dashboard): remove GitHub link and button group

- Remove the GitHub link button and related styles from the web dashboard page
- Simplify the page layout by eliminating the button group section

Author: fulleni

src/content/docs/web-dashboard/index.mdx

@@ -33,15 +33,3 @@ The Flutter News App Web Dashboard is a comprehensive, production-ready web appl
 		[Read more →](/docs/web-dashboard/manuals/managing-content/)
 	</Card>
 </CardGrid>
-
-<div class="button-group">
-    <LinkButton href="https://github.com/flutter-news-app-full-source-code/flutter-news-app-web-dashboard-full-source-code" icon="github" variant="secondary">Browse on GitHub</LinkButton>
-</div>
-
-<style>
-	.button-group {
-		display: flex;
-		gap: 1rem;
-		margin-top: 2rem;
-	}
-</style>