fix: header

Author: lawmicha

src/pages/[platform]/build-a-backend/data/aws-appsync-apollo-extensions/index.mdx

@@ -38,7 +38,7 @@ To learn more about Apollo, see https://www.apollographql.com/docs/kotlin.
 
 </InlineFilter>
 
-### Features
+## Features
 
 AWS AppSync Apollo Extensions provide AWS AppSync authorizers to be used with the Apollo client to make it simple to configure runtime interceptors and apply the correct authorization payloads to your GraphQL operations.